CSIT Family An online CSIT community

### Electric and Magnetism

66.n-equal capacitors are first connected in series and then in parallel. The the ratio of maximum to minimum capacitance 

n2

1/n2

n

1/n

67.A wire of resistance 12Ω is bent to form a circle.The effective resistance between the two points on any diameter of circle is 

12Ω

9Ω

6Ω

3Ω

68. The resistance of an ideal ammeter is 

0

low

high

infinite

69. A 10 eV electron is circulating in a plane at right angles to a uniform field of magnetic induction 10-4, the orbital radius of the electron is 

18cm

16cm

11cm

9cm

70. Whenever the magnetic flux linked with a coil changes,there is emf induced in the circuit the emf last 

For a short time

For a long time

Forever

so long as the change in flux takes place

69. Wheat stone bridge is used to measure 

emf

potential

current

resistance

70. Magnetism of a magnet 

is zero at absolute zero temperature

increase with temperature

is maximum at curie temperature

becomes practically zero above curie temperature

71. The self inductance of coil is MH. If a current of 2a is flown. What is the magnetic flux through coil? 

0.02 Wb

0.01 Wb

0.05 Wb

10 Wb

64. An isolated conducting sphere is given a positive charge. It's mass 

increases

decreases

remains constant

may increase or decrease depending on the material

65. Three capacitors each of capacitance 3pF are connected in series. The net capacitance is 

1μF

(1/3)μF

3μF

9μF

66. Kirchoff's voltage law is based on the principle of conservation of. 

charge

energy

momentum

mass of charges

67. A charged particle is in a strong magnetic field. Then its kinetic energy 

increase

decrease

remain constant

increase and become constant

68. The self-inductance of a straight wire is 

zero

infinity

negative

positive

71. On increasing the reserve bias to a large value in a p-n junction diode, the current 

increase slowly

remains fixed

decreases slowly

suddenly increases

67. A 25W, 120V lamp and 100W, 120V lamp are connected in series across a 120V line. Which lamp will burn more brightly

25W, 120V

100W, 120V

Both will have same brightness

Alternatively both may be bright, one at a time.

70. A 0 - 100mA resistance 1ft is to be converted to an ammeter in the range of 0-1A. We have to use shunt 

0.1Ω

0.111Ω

0.055Ω

68. A system of three charges may be in equilibrium . If they are placed

On a straight line

On corners of equilateral triangle

On three corners of rectangle

On the corners of a cube

69. The radius of Earth 6400 km. The capacitance is 

6400 MF

6400 F

1 F

711 μF

70. Two wire of same material have lengths L and 2L and are cross reaction areas 4A and A respectively. The ratio of their specific resistance would be 

1:1

1:8

8:1

1:2

71. The magnetic field induction inside a long solenoid is

zero

0ni

μ0ni

μni

64. Three capacitor of capacitance 3µF, 9µF and 18µF are connected first in series and then I parallel. the ratio of C equivalent capacitance in two cases (CI/CP) will be/p>

1:15

15:1

1:1

1:3

65. Three equal registers each of resistance 'r' are connected to form a triangle. The equivalent resistance across any two comes of the triangle is.....

2r

r/3

2r/3

3r

66. The resistance of two lamp are in ratio of 1:2. Their wattage will be in the ratio of 

1:2

2:1

4:1

1:4

67. The energy stored in 50mH inductor carrying a current of 4A is ....... 

0.1 J

0.4 J

0.3 J

0.01 J

68. The alternating current in an LCR circuit is maximum when 

XL = 0

XC = 0

XL = XC

$\sqrt{X{{}_{L}}^{2}+X{{}_{C}}^{2}}$

73. A common emitter transistor amplifier has a current fain of 50. If the load resistance is 4 kΩ and the input resistance is 500 Ω. The voltage gain on the amplifier is ....... 

400

6.2

500

300

64. Watt per ampere is the unit of 

electric potential

electric field intensity

electric power

electric energy

65. Two wires A and B of equal radii are drawn from the same material. Their lengths are 1m and 2m respectively. The resistivity of A is. 

less than that of B

equal to that of B

more than that of B

depends upon the amount of current flowing in wires

66. When a capacitor is added in series in an LCR circuit, the impedance of the circuit 

increase

decrease

remain unchanged

increases or decreases depending upon the frequency of a.c

67. A cell of emf X if connected across a resist of R. The potentional difference across the wire is measured as Y. The internal resistance of the cell should be 

X - (Y/R)

(X-Y)R

(X-Y)R/X

(X-Y)R/Y I there is