Current Electricity MCQ Level - 2 - Physics MCQ

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 :

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).

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

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 :

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:

A cylindrical solid of length L 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 :

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 :