# Current Electricity MCQ Level - 2

## 10 Questions MCQ Test Basic Physics for IIT JAM | Current Electricity MCQ Level - 2

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Attempt Current Electricity MCQ Level - 2 | 10 questions in 45 minutes | Mock test for Physics preparation | Free important questions MCQ to study Basic Physics for IIT JAM for Physics Exam | Download free PDF with solutions
QUESTION: 1

Solution:

50 = 10[R + r]

QUESTION: 2

Solution:

QUESTION: 3

### ‘n’  identical light bulbs, each designed to draw P power from a certain voltage supply are joined in series and that combination is connected across that supply. The power consumed by one bulb will be :

Solution:

For series combination, the total power is:
1/Pt = 1/P1 + 1/P2 +.........+1/Pn
= 1/P + 1/P +..............+ upto n
= n/P
Therefore, Pt = P/n

QUESTION: 4

A copper sphere of 10cm  diameter is lowered into a water filled hemispherical copper vessel of 20cm  diameter so that the sphere and the vessel becomes concentric. Electrical conductivity of water of  σ = 10-3(Ωm)-1. The electrical resistance between the sphere and the vessel is :

Solution:

The arrangement is shown in figure. Consider the hemispherical shell of radius r and thickness dr as shown.

QUESTION: 5

When a galvanometer is shunted with a 4Ω resistance, the deflection is reduced to one-fifth. If the galvanometer is further shunted with a 2Ω wire, the further reduction (find the ratio of decrease in current to the previous current) in the deflection will be (the main current remains the same).

Solution:

Case I

Case II

so decrease in current to previous current

The correct answer is: (8/13) of the deflection when shunted with 4Ω only

QUESTION: 6

In the circuit shown, the value of R in ohm that will result in no current through the 30V battery, is:]

Solution:

Potential drop across R = Potential drop across AB

QUESTION: 7

In the shown wire frame, each side of a square (the smallest square) has a resistance R. The equivalent resistance of the circuit between the points A and B is :

Solution:

Hence equivalent resistance between A  and B  is 2R.

QUESTION: 8

Two long coaxial and conducting cylinders of radius a and b are separated by a material of conductivity σ and a constant potential difference V  is maintained between them, by a battery. Then the current, per unit length of the cylinder flowing from one cylinder the other is:

Solution:

where is the linear charge density on the inner cylinder

Current per unit length will be :

QUESTION: 9

A cylindrical solid of length and radius a  is having varying resistivity given by  ρ = ρ0x  where ρ0 is a positive constant and x is measured from left end of solid. The cell shown in the figure is having emf V and negligible internal resistance. The electric field as a function of x is best described by :

Solution:

Consider an elemental part of solid at a distance  x  from left end of width dx.
Resistance of this elemental part is,

Current through cylinder is,
Potential drop across element is,

QUESTION: 10

In a practical wheat stone bridge circuit as shown, when one more resistance of 100Ω is connected is parallel with unknown resistance x, then ratio ℓ1/ℓ2 become 2, ℓ1 is balance length. AB is a uniform wire. Then value of x  must be :

Solution:

∵  wheat stone bridge is in balanced condition