physics 1 marks

1.ELECTROSTATICS
1. Two capacitors of 20 mF and 35 mF are charged to a potential of 120 V each. When they are connected in parallel, the potential across them is ____________
a. 60 V each b.100 V each c. 120 V each d. 240 V each ( c)

2. The component used in tuning the radio circuit is ____________a. resistors b. capacitors c. transistors d. diodes (b)The equivalent capacitance of (n + 1 ) identical capacitors connected in series is
a. (n + 1 ) C b. 1 / (n + 1) C c. (n + 1) / C d. C / (n + 1) (d)

3. A glass rod rubbed with silk acquires a charge +8 x 10-12 C. The number of electrons it has gained or lost _____________
a. 5 x 10-7(gained) b. 5 x 107(lost) c. 2 x 10-8(lost) d. –8 x 10 –12 (lost) (b)

4. Electric field intensity is 400 V m-1 at a distance of 2 m from a point charge. It will be 100 V m-1 at a distance ?
a. 50 cm b. 4 cm c. 4 m d. 1.5 m (c)

5. A dipole is placed in a uniform electric field with its axis parallel to the field. It experiences ______________
a. only a net force b. only a torque c. both a net force and torque
d. neither a net force nor a torque. (d)

6. In a hydrogen atom, the electron and proton are bound together at a separation of about 0.53 Ǻ. If the potential energy is zero at infinite separation, then the potential energy of the electron proton system is ____________
a. –54 4 eV b. –27.2 eV c. –13.6 eV d. zero (b)

7. The number of electric lines of force originating from a charge of 1 C is _________
a. 1.129 x 1011 b.1.6 x 10-19 c. 6.25 x 1018 d.8.85 x 1012 (a)

8.The meaning of the Greek word electron is ______________
a. electricity b. Charge c. amber d. glass (c)

9.The property of attraction and repulsion between charged bodies is not used in ________
a. fly – ash collection in Chimneys b. ink – jet printing c. Xerox machine
d. Cordless phones (d)

10.The total force F on q0 due to an entire surface charge distribution is given as __________
a. F = q0 ò a b. F = q0 ò a c. F = q0 d. F = q0 ò a
4pe0 4pe0 4pe0 r2 4pe0
(b)

11. Electric potential energy of an electric dipole in an electric field is given as _______
a. PE sin q b. –PE sin q c. PE cos q d. –PE cos q (d)

12. The electric dipoles in micro oven are ____________
a. the food molecules b. water molecules c. water molecules in the food
d. microwaves. ( c)

13.Electric field due to uniformly charged sphere of radius R at a point on the surface is ________
a. E = q / 4pe0 R b. E = q / 4pe0 r c. E = q / 4pe0 R2 d. E = 0 ( c)

14. The electric field inside an electrostatic shielding is ____________
a. E = 0 b. infinity c. E = q / 4pe0 r2 c. q / 4pe0 R2 (a)

15.The angle between the direction of electric field and an equipotential surface is ________
a. zero b.900 c. 1800 d. 600 (b)

16.The induced dipole moment is given as ______________
a. P = E b. P = a / E c. P = a E d. P = a ( c)

17.The working principle of Vande Graff generator is ____________
a. action of points b. electrostatic induction c. action of points and electrostatic induction d. None of these ( c)

18.If the distance between two charges is doubled the electrostatic force between the charges will be _____________
a. four times more b. four times less c. will increase two times
d. will decrease two times (b)

19.If a proton is moved against the coulomb force of an electric field __________
a. work is done by the electric field
b. energy is used from some outside source
c. the strength of the field is decreased
d. the energy of the system is decreased (b)

20.The permittivity of vacum equals ___________
a. 9 x 109 Nm2 C-2 b. 1 c. –1 C2 N-1 m-2 d. 1 C2N-1 m-2
9 x 109C2N-1M-2 4 p x 9 x 109(d)

21.If two capacitors of capacitance 2 mF and 6 mF are put in series, the effective capacitance of the system is _____________
a. 8 mF b. 2 mF c. 3/2 mF d. 2/3 mF ( c)

22.In between two like charges there is _______________
a. a force of attraction b. a force of repulsion c. no action d. infinite force. (b)
The force between two point charges is directly proportional to the product of the charges and inversely proportional to the square of the distance between them. This is known as _________
a. Ampere’s law b. Maxwell’s law c. Coulomb’s law d. Gauss’s law ( c)
In nature the electronic charge e and a charge q are related as ___________
a. n/e = q b. q/n = e c. e/n = q d. n/q = e (b)

23.The value of permittivity of free space (e0) is ____________
a. 8.854 x 10-12C2 N-1 m-2 b. 8.854 C2 N-1 m-2 c. 8.854 x 1012C2 N-1 m-2
d. 8.854 x 10 9C2 N-1 m-2 (a)

24.The relative permittivity of air is ______________
a. 0 b. 1 c.1000 d.¥ (b)

25.Two dissimilar charges separated by a small distance constitute an ___________
a. electric dipole b. electric moment c. electric field d. electric potential (a)

26.The direction of electric dipole moment is ____________
a. from –q to +q b. from +q to –q c. along the perpendicular bisector of the line joining +q and –q d. inclined to the line joining +q –Q (a)

27.The tangent to the electric line of force at any point gives ____________
a. the potential at that point b. the strength of electric field
c. the direction electric field at that point d. magnetic line ( c)

28.The work done in moving a unit positive charge, from a point where the potential V1 to another of V2 is ________________
a. V 1 – V2 b. V2 – V1 c. V1V2 d. zero (b)

29.The electric potential at infinity from a point charge q is ______________
a.zero b.infinity c. 2q d. q/2 (a)

30.The potential energy of a system of charges 3C and 3C separated by a distance of 9 m is ________
a. 3 x 109 Joules b. 9 x 109 Joules c.27 x 109 Joules d. 1/9 x 109 Joules (b)

31.The electric potential at any point on the equatorial line of a dipole is _________
a.zero b.infinity c. P/4pe0 r d. P / 4pe0 r3 (a)

32.The electric potential at a point due to a charge +q at a distance d is given as _______
a.V= q/ 4pe0 d b. V= + q/ 4pe0 d c. V= - q/ 4pe0 d2 d. V= + q/ 4pe0 d2
(b)

33.The unit of electric flux linked with a closed surface is _______________
a. Nm2 C-1 b. Nm2 C-1 c. Nm2 C2 d. c. Nm-2 C (a)

34.The electric field at a point due to an infinite plane sheet of charge is
a. E = s / 2e0 b. E = s / 2e0 c. E = e0 / s d. E = 2e0 / s (a)

35.The resultant field at an outside point due to two parallel sheets of charges is _________
a. zero b. infinity c. s / 2e0 d. s / e0 (a)

36.In a circular plate the charges accumulate at __________
a. the center b. at the surface area c. at the edges
d. entire surface including edges. ( c)

37.The working principle of Electrophorus is ____________
a. Self induction b. Mutual induction c. electrostatic induction d. electromagnetic induction ( c)

38.The capacitance of a conductor can be found out using the formula
a. c= V / Q b. c = Q / V c. c = QV d. c = 1 / QV (b)

39.The dielectric constant of mica is ______________
a. 6 b.4 c. 7 d. 5 (a)

40.The total flux over a closed surface enclosing a charge q is __________
a. 9 x 109 q b. 4pq c. 36 pq d. 36p x 109 q (d)

41.When an insulated metal plate B is brought nearer to the insulated metal plate A the potential of A __________
a. increases b. decreases c. does not change d. becomes zero (b)

42.The expression for the capacitance of a capacitor with a dielectric slab is given as ________
a. C = e0A b. C = e0A c. C = er e0A d. C = er (a) (d – t) + t/er (d – t) + t / e0 (d – t) + t / e0 e0 A(d – t) + t
43.The dipole in a uniform field experiences___________
a. no force b. a force c. a torque d. a dipole moment ( c)

44.The work done in moving a unit +ve charge in a uniform electric field is ____________
a. infinity b. maximum c. minimum d. zero (d)

45.Let the potential at a point be V. What is the work done in carrying –5 coloumb of charge from infinity to that point ?
a. – V / 5 Joules b. 5 V Joules c. –5 V Joules d. V / 5 Joules
( c)

46.The electric potential at a point due to a charge of 100 micro coulomb at a distance of 9 metres is ____________
a. 9 V b. 100 V c. 100 micro volt d. 10 5 V (d)

47.Three capacitors C1,C2 and C3 are connected in series. The effective capacitance is 24/11 mF. If C1 and C2 are 4 mF and 8 mF respectively, the capacitance of the third one is ___________
a. 4 mF b. 12 mF c. 8 mF d. 32 mF (b)

48.The charge on a given capacitor is 5 C and its capacitance is 2 mF. If the charge on the capacitor is doubled, then the capacitance is _____________
a. 2mF b. 4mF c. 10 mF d. 2.5 mF (b)

2. CURRENT ELECTRICITY
1.The value of the carbon resistor whose colours are red, green, yellow is ________
a. 250 W b. 230 W c. 230 K W d. 250 KW (d)

2.The amount of charge in a metallic wire is 5 x 107C. If the current density in the wire is 3 x 105 C , the drift velocity of the electron is ____________
a. 1.67 x 102 ms-1 b. 6 x 10 3 ms-1 c. 6 x 10 -3 ms-1 d. 3 x 10 13 ms-1
(c)

3.The potential developed between two ends of conductor is 25 volts. 2A current flows through it. The conductance of the conductor is ____________
a. 80 mho b. 80 milli mho c. 80 micro mho d. 40 mho (b)

4.A resistance wire is cut into 4 equal parts and all the four parts are connected in parallel. The ratio of the effective resistance to the original resistance is ________
a. 1 : 2 b. 2 : 1 c. 4 : 1 d. 1 : 4 (d)

5.The resistance of a conductor is 5 W at 500 C and 6 W at 1000 C. Then the resistance at 00 C is ____________
a. 0 W b. 3.5 W c. 4 W d. 8 W ( c)

6.A charge of 60 C passes through an electric lamp in 2 minutes. Then the current in the lamp is ___________
a. drift velocity b. 1 / area of cross section c. 1 / no of electrons
d. square of area of cross section ( c)

7.The current flowing in a conductor is proportional to ___________
a. drift velocity b. area c. 1/no. of electrons d. (area)2 (a)

8.According to Faraday’s law of electrolysis, when a current is passed, the mass of ions deposited at the cathode is the independent of ________
a. current b. charge c. time d. resistance (d)

9.The current always flow from _________
a. Positive or negative b. Negative to positive
c. Zero potential to zero potential d. Positive to positive (a)

10.The external energy necessary to drive the electrons in a definite direction is called _____
a. Force b. Electromotive force c. Potential difference d. Current (b)

11.The current I is expressed as ___________
a. i = q x t b. i = q / t c. i = t / q d. i = 1 / qt (b)

12.The unit of conductance is ____________
a. ohm b. mho c. ohm.m d. mho.m (b)

13.Ohm’s law is true only when _____________
a. temperature increases b. temperature decreases
c. temperature neither increases nor decreases d. temperature increases and decreases
( c)

14.The unit of conductivity is __________________
a. mho b. ohm c. ohm.m d. ohm-1 m-1 (d)

15.The drift velocity is in the order of ________________
a. 0.1 ms-1 b. 0.1 mms-1 c. 0.1 cms-1 d. 0.1 kms-1 ( c)

16.The expression for mobility is ____________
a. m = m b. m = E e c. m = E e d. e t
e t m m m (d)

17.The unit of mobility is ____________
a. ms-1 b. m2 ms-1 c. m2 v-1 ms-1 d. m-1 s ( c)

18.The specific resistance of metals and alloys is in the order of ____________
a. 106 to 10 -8 W m b. 106 to 108 W m c. 10-8 to 10 -10 W m d. 108 to 10 -10 W m (a)

19.The phenomenon of super conductivity occurs only at _______
a. very low temperature b. very high temperature c. room temperature
d. moderate temperature (a)

20.The conductivity of super conductors is ____________
a. zero b. very low c. infinity d. very high (a)

21.The super conducting transition temperature of mercury is _______________
a. 4.20C b. 268.80C c. -268.80C d. 00C ( c)

22.Current in a super conducting wire can flow __________
a. without change in magnitude b. without change in magnitude and direction
c. with the change in magnitude d. with the change in energy (a)

23.The silver or gold ring on a carbon resistor corresponds to ________
a. first number b. second number c. powers of 10 d. tolerance (d)

24.The grey colour ring on a carbon resistor corresponds to ___________________
a.1 b. 2 c. 9 d. 8 (d)

25.The blue colour ring on a carbon resistor corresponds to ________________
a. 4 b. 3 c. 5 d. 6 (d)

26.The tolerance of silver ring is _____________
a. 1% b. 2% c. 5% d. 10% (d)

27.In the parallel combination of resistors ___________ is the same.
a. current b. potential difference c. resistance d. all the three (b)

28.Thermistor is a material with ___________ temperature coefficient of resistance
a. low and +ve b. high and +ve c. negative d. ¥ ( c)

29.The formula to find the internal resistance of a cell is _______________
a. r = – V b. r = V c. r = E d. r = V
V E - V V E (a)

30.The other name of Kirchoff’s II law is ____________
a. power law b. voltage law c. current law d. resistance law ( c)

31.In which of the following Kirchoff’s laws are used ______
a. Potentiometer b. Wheatstone’s c. Ammeter d. Voltmeter (b)

32.The bridge wire in metre bridge is made up of __________
a. Steel b. Copper c. Nichrome d. Manganium (d)

33.The formula to calculate the resistivity of the material of a wire is __________
a. s = P r2/ L b. s = Pp r/ L c. s = Pp r2 / L d. s = P r / L ( c)

34.The emf (E) connected in the secondary of a potentiometer is ______________
a. E = i2 r l b. E = i r l c. E = i r2l d. e = i r l2 (b)

35.The emf is ______________
b. directly proportional to the resistance in the external circuit
c. inversely proportional to the resistance in the external circuit
d. independent of the resistance in the external circuit
e. is a force (c)

36..The instrument used to measure electric power is _______________________
a Ammeter b. Multimeter c. Wattmeter d. Voltmeter ( c)

37.Mass of the substance liberated at an electrode during electrolysis is ___________
a. m = z i2 t b. m = z2 i t c. m = z i t d. m = z i t2 ( c)

38.Primary cell is a device which converts ____________
a. electrical energy into chemical energy b. chemical energy into electrical energy
c. chemical energy into kinetic energy d. heat energy into electrical energy (b)

39.The anode in Daniel cell is ____________
a. zinc rod b. copper rod c. copper vessel d. glass vessel ( c)

40.The anode in Lechlanche cell is ____________
a. zinc rod b. copper electrode c. copper vessel d. carbon rod (d)

41.The current from Lechanche cell is ____________________
a. 1 A b. 0.5 A c. 2 A d. 0.25 A (d)

42.Which of the following is the anode in dry cell ?
a. zinc bottom b. carbon rod c. copper bottom d. zinc rod (b)

43.The electrolyte used in a dry cell is ______________
a. brass rod b. sal ammoniac paste c. MnSO4 + powdered carbon
d. CuSO4­ solution (b)

44.The cathode in Lead acid accumulator is _______________
a. PbO2 b. spongy – lead c. carbon plate d. copper plate (b)

45.The specific gravity of the electrolyte in Lead – Acid accumulator __________
a. 1.2 b. 1.284 c. 1.28 1.82 ( c)

3.EFFECTS OF ELECTRIC CURRENT
1. The magnetic induction at the center of a coil of 250 turns, radius 0.25m and
carrying a current of 6A is…………….
[ a. 12p x 10-4 T (b).3.768 x 10-4 T (c).12p x 10-3 T (d).37.68 x 10-3 T ] (a)
2. A.T.G. gives a deflection of 45o when a current of 2A flows through it. Then the
deflection of 60o produced a current of ……………
[ a. 35mA (b) 350 mA (c) 3.7A (d).3.5A ] (d)
3. When the charge is at rest, then the magnetic Lorentz force is …………..
[ a. minimum (b).maximum (c).zero (d).infinity (c)
4. The shunt resistance of the ammeter having a galvanometer of resistance 300 W
to divert 75% of the total current is ……………
[ a. 50W (b).80W (c).100W (d).200W ] (c)
5. Two wires each carrying a current of 600A in the same direction are placed with
their axes 0.3 m apart. The force between them per metre length is …………
[ a. 24 N (b).0.24 N (c).240 N (d).2.4N ] (b)
6. The number of turns of a coil of radius 20 cm required to produce a magnetic field
of 5p x 10-4 T at the center with a current of 5A is …………….
[ a. 50 (b).25 (c) 500 (d) 100 (d)
7. Nichrome wire is used as the heating element because it has ……………
[ a. low specific resistance (b).low melting point (c).high specific resistance
(d).high conductivity ] (c)
8. In a thermocouple, the temperature of the cold junction is 20oC, the neutral
temperature is 270oC. The temperature of inversion is …………..
[ a. 520oC (b).540oC (c).500oC (d).510oC ] (a)
9. In a tangent galvanometer, for a constant current, the deflection is 30o. The plane
of the coil is roated through 90o. Now for the same current, the deflection will be .
[ a. 30o (b).60o (c).90o (d).0o ] (d)
10. Phosphor – bronze wire is used for suspension in a moving coil galvanometer,
because it has ………….
[ a. high conductivity (b).high resistivity (c).large couple per unit twist
(d).small couple per unit twist ] (d)
11. The heating element in electric iron is made up of ……………
[ a. manganin (b).copper (c).steel (d) nichrome (d)
12. The fuse wire is an alloy of …………
[ a. tin 63%, lead 37% (b).Ni 63 % tin 37% (c).Ni 67% chromium 33%
(d).lead 63% tin 37% ] (a)
13. The melting point of tungsten is ………..
[ a. 3386oC (b).3368oC (c).3380oC (d).3830oC ] (c)
14. In which one of the following the heat production is minimized ?
[ a. electric iron (b).electric bulb (c).transformer (d).electric oven (c)
15. In a Fe-Cu thermocouple the direction of current is ………
[ a. iron to copper at the cold junction (b).iron to copper at the hot junction
(c). clockwise (d).anticlock wise (a)
16. Beyond the temperature of inversion the thermo emf ………….
[ a. invreases (b).changes its sign and increases (c).does not increase
(d).neither increases nor decreases (b)
17. Peltier effects is the converse of …………….
[ a. Joule’s effect (b).Thomson effect (c).Seebeck effects (d).Raman effect (c)
18. The unit of Thomson coefficient is ……………
[ a. volt (b).ampere (c).coulomb (d).per oC (d)
19.The working principle of thermopile is ………….
[ a. Thomson effect (b).Peltier effect (c).Seebeck effect (d).Joule effect ] (c)
20. The deflection in the galvanometer of a thermopile is proportional to ………….
[ a.frequency of radiation (b).wavelength of radiation (c).velocity of radiation
(d).intensity of radiation ] (d)
21. The unit of magnetic induction is …………..
[ a. Weber (b).Weber –m (c).Weber –m-2 (d).Ampere –m ] (c)
22. The magnetic induction at the center of a circular coil carrying current is given as
µo n1a2 µo n1 µo a1 µo na
[ a. B= ---------------- (b).B = ----------------- (c).B = --------- (d).B= -----------] (a)
2(a2 +x2) 3/2 (a2 + x2 ) 3/2 2n 21
23. The most generalized way of writing Ampere’s circuital law is ……….
→→ → → μo 1
[ a. ƒ B.d1 =µo10 (b)B. d1 =μo 1 (c) BL = μo 1o (d).B = --------- ] (a)
2πa
24. The magnetic polarity of the current carrying solenoid is givent by ………….
[ a.Fleming’s left hand rule (b).Maxwell’s cork screw rule
(c).End rule (d).Right hand palm rule ] (c)
25. The magnetic Lorentz force is given as ……………
[ a. F = BqV sin 0 (b).F= Bqv cos 0 (c).F = Bqv tan 0 (d).F = Bq ] (a)
26. Torque on a current loop placed in a magnetic field is given as ………
[ a. t =nBA sin 0 (b).t=nBIA sin 0 (c).t=nBIA (d).t=nBia cos 0 ] (b)
27. If the coil is parallel to the magnetic field the torque is …………
[ a. zero, (b).minimum (c). maximum (d).infinity ] (c)
28. Current sensitivity of a galvatometer is ……………
0 nBA 0 C 0 0
[ a. ----- = ---------- (b). ---- = ----- (c). ----- = nBA (d). ----- = nBAC ] (a).
1 C 1 nBA 1 1
29. The voltage sensitivity of a galvanometer is given by expression ………….
_O_ IG_ CG0 0_
[ a. nBA (b). 0 (c). nBA (d). IG ] (d)
30. If the number of turns in a galvanometer is doubled ………………..
[ a. the current sensitivity is halved (b).the voltage sensitivity is halved
(c).voltage sensitivity remain unchanged (d).the voltage sensitivity is halved (c)
31. Ideal voltmeter has ………………. resistance.
[ a. zero (b).minimum (c). maximum (d).infinity ] (d)
32.Gyromagnetic ratio of an electron is …………….
[ a. 1.602 x 10-10 C (b).7.95 x 10-10C Kg-4, (c).8.8 x 10-10 Kg-1
(d). 8.8 x 10-10 C Kg-1 ] (d)
33. The expression for Bohr magneton is …………….
h eh h nh
[ a. ----------- (b) ________ (c) ______ (d) ________ ] (b)
2πm 4πm 4πm 2π
34. Positive charges will always move from ………………..
[ a. higher potential to lower poterntial, (b).lower poterntial to higher potential
(c).zero poterntial to higher potential (d).zero potential to lower potential.] (a)
35. In a thermocouple the emf produced at neutral termperature is ……………
[ a. zero (b).maximum (c).minimum (d).infinity ] (b)
36. The expression connecting the neutral temperature Tn temperature of inversion
T1 and temperature of cold junction Tc of a thermocouple is
Tn + Tc T1 + Te Tn + T1
(a).T1= 2 (b) Tn= 2 (c).Tc = 2 (d).T1 = Tn + Tc (b)
37. The until of Peltier coefficient is …………….
(a). Joule (b).Volt (c).Ampere (d).Ohm. (b)
38. For which of the following Thomson effect is negative ?
(a).Sb (b).Zn (c).Co (d).Cu (c)
39. At the center of a circular current carrying coil the magnetic lines of force are ….
(a).straight (b).circular (c).zig zag (d).irregular (a)
40. Which law is used to calculate the magnetic induction due to current carrying
conductor ?
(a).Kirchoff’s law (b).Gause law (c).Biot-Savart law (d).Ampere’s law (c)
41. The magnetic induction at the center of a circular loop due to the flow of current in
it is …………..
μo I μo I I μo I
(a).B = ------- (b).B = --------- (c).B = ------- (d). _____ (b)
r2 2r 2r r
42. Magnitude of force on a current carrying conductor placed at an angle 0 with the
direction of magnetic field is ………….
(a). F = B1 / cos 0 (b).F=BI / tan 0 (c).F=BI / sin 0 (d).F = BI / 0 (c)
43. If a current carrying conductor is placed parallel to the direction of magnetic field
the force is …………..
(a).F = BI / (b).F = -BI / (c). F = ∞ (d). F = 0 (d)
44. The expression for the radius of the orbit of a charged particle in a uniform
magnetic field is ………….
Bq mv Bqm Bqv
(a). r = ------- (b).r = -------- (c). r = --------- (d).r = -------- (b)
mv Bq v m
45. The working principle of a moving coil galvanometer is ……………..
(a). Fleming’s left hand rule (b).Fleming’s right hand rule
(c). Ampere’s swimming rule (d).Right cork screw rule (a)
46. In a moving coil galvanometer the deflection is ……………
(a).directly proportional to the current (b). inversely proportional to the current
(c).directly proportional to 12 (d). inversely proportional to 12 (a)
47.Shunt is a resistance of …………….
(a). low value connected in a series with galvanometer
(b). high value connected in parallel with galvanometer
(c). high value connected to series with galvanometer
(d). low value connected in parallel with galvanometer (d)
48. The value of shunt resistance in an ammeter of range I ampere is given as ……
1 1g I - Ig I - Ig
(a). S = G { -------- } (b).S = G{ ---------} (c).S=G{ --------} (d).S=G {---------} (b)
1 – 1g I -Ig Ig I
49. A galvanometer can be converted into an ammeter by connecting a …………
(a).low resistance in parallel (b). high resistance in parallel
(c).low resistance in series (d). high resistance in series (d)
50.The value of R connected with a galvanometer into a voltmeter is given by the
expression
G + V V G-V
(a).R= {---------} (b).R={------ -G} (c).R= Ig {v+G } (d).R={--------} (b)
Ig Ig Ig
51.For full scale deflection the needle of a multimeter requires current ranging from..
(a).0.05 mA to mA (b).0.5 mA to 10 mA (c)1 mA to 100 mA (d).100mA to 1A (a)
52.As the range of voltmeter increases the value of resistance in series ………
(a). increases (b).decreases (c).remains the same (d).becomes zero (a)

4. ELECTROMAGNETIC INDUCTION AND ALTERNATING CURRENT
1.A coil of 50 turns and area of cross-section of 0.1m2 has its axis perpendicular to a
magnetic induction of 0.9 wb / m2, then the flux passing the coil is …………
(a).4.5Wb (b).45 Wb (c). 0 (d).4.5 m.Wb (c).
2.The self inductance of a coil is equal to the magnetic flux linkage of the coil, when
the current through the coil is ……………
(a). I A (b). I A / S (c). 2 A (d). constant. (a)
3.For d.c.the capacitor offers …………..
(a).infinite resistances (b).zero resistance (c).maximum resistance,
(d). minimum resistance. (a)
4.The coefficient of self induction of a coil of 1000 turns which produces a magnetic
flux of 0.5 Wb for a constant current of 2.5 A is ………
(a).4 x 102 H (b).4 x 10 –2 H (c). 2 x 10-2 H (d).2 x 102 H (d)
5.In a step up transformer the input voltage is 22o V and the output voltage is 11kV.
The ration of number of turns of secondary to primary is ………….
(a).20 : 1 (b).22.1 (c).50.1 (d).1.50 (c)
6.Electromagnetic induction is not used in…………..
(a).transformer (b).roomheater (c)Acgenerator (d)choke coil (b)
7.Lenz’s law is in accordance with the law of…………
(a).conservation of charges (b).conservation of flux
(c).conservation of momentum (d).conservation of energy (d)
8.The unit henry can also be written as ………..
(a).Vs A –1 (b).Wb A-1 (c). Ω s (d). all (d)
9.Transformer works on ………….
(a). AC only (b).DC only (c).both AC and DC (d).AC more effecrively than DC (a)
10.Which of the following cannot be stepped up in a transformer >
(a). input current (b).input voltage (c).input power (d).all (c)
11.in an ac circuit …………..
(a).the average value of current is zero,
(b).the average value of square of current are more
(c).the average power dissipation is zero
(d).the rms current is √2 time of peak current (a)
12. If the core of a long xolenoid is filled with a magnetic material of permeability
µ then ……………
µo N2A µ2NA µoNA µN2A
(a).L = -------------- (b),L = ---------- (c). ---------- (d). ---------- (d)
l l l l
13.The coefficient of mutual induction between two coils is given as …………
N1N2A µoN1N2A e2 l1
(a).M = ------------ (b). M = ------------- (c).M = ------- (d).M= ----- (b)
l l l1 l2
14.A polyphage generator produces voltage waves equal to ……………
(a). number of rotations of the coil per second (b). number of phases
(c). number of ends of the coils (d). all the above (b)
15.In a step up transformer the transformer ratio (k) ………………
(a).K=O (b).K>1 (c).K<2 k="1" power =" output"> output power (d).input power < p=" ---------" p=" -------" p=" I" p="I" f="B" f ="∳" e =" --------" e =" -------" e =" N" e=" ------" e=" ------" e =" -" e =" -" e =" -" eo =" -----------" eo =" ------" eo =" NABω" eo =" --------" i =" Io" i ="Io" i =" Io" i =" ------" v =" √" v =" √" v =" √" v =" √" z =" √R2" z =" √R2" z =" √" z =" √R2" l =" X" m =" sin" m =" sin" m =" 1" m =" sin" f =" l" f =" l" f =" 2" f =" 2" r =" (2" r =" n" r =" (2" r =" n" stl =" q" stl =" q" stl =" C" stl =" q" e =" hv" e =" h/" e =" 1" e =" v" r4 ="ÖRl" rn=" ÖnR" rn="Ö(n" rn =" Rl" e =" V" e =" d" e =" BeV" e =" Vd" r0 =" 1" r0 =" 1" r0 =" 4Ze2" r0 =" 1" dl =" -1" dl =" -" dl =" ml" di =" -" lmin ="12400" lmin =" V" lmin =" V" lmin =" 12400" g =" aZ" g =" a(Z2" g =" Z2" g =" a(Z" a =" 9hV" a =" 9" a =" 9hV" a =" 9hV" l =" 2" nl =" 2" q =" 2" nl =" sin" ek =" -" ek =" -" ek =" +" ek =" -" ev0 =" mV2max" ev0 =" ½" ev0 =" ½" v0 =" ½" l =" mv" l =" m" l =" h" l =" v" h2 ="2.01473" becquerel =" _____________" t =" 0.6931" t =" 0.6931l" t =" l" t =" 1/0.6931" b =" 0.1" b =" 1" b =" 1" b =" 0" 1 =" ?" a =" b" b =" 2." a =" b" b =" a" av =" Zi" av =" Rl" av =" Rl" av =" Rlb" b =" C" b =" C" b=" A" b =" C" d =" A." d =" AB" d =" (A" d =" A" m =" ______________" es =" Ec" es =" Es" es =" Ec" es =" Es">