Current Electricity MCQ Level - 3

We know, Resistance depend on temperature by relation.

R₁₀₀ = 4(1 + 0.0038 × 100)
R₁₀₀ = 4(1 + 0.38)

The correct answer is: 5.52Ω

Let us impart charge  q  and  –q  to the balls respectively. Potential difference between two balls

V = V₊ – V_–

Electric field at the surface of first sphere

electric field due to second sphere at the surface of first sphere is negligible
current density J = σE

The electric current

The correct answer is: Increases

Applying boundary condition of 

Dividing (2) by (1)

The correct answer is: 

As the current flow from inner to outer shell, the cross-section area increase. Assuming an element in form of spherical shell of radius r  and thickness  dr

The resistance

Net resistance

The convection current is

Here, dq = λdx. where λ is the linear charge density. But, from the gauss, theorem, electric field at the surface of the cylinder,

Hence, substituting the value of λ and subsequently of dq  in Equation (i), we get

The correct answer is: 

We know, current through conductor = I = neAv_d
where A = Area
v_d = drift velocity
e = charge on electron
n = number of electron per unit volume

The correct answer is: 1.25 × 10^–5 m/s

The current density

J = I/A

Electric field in the two conductor are given by

If we consider of Gaussian pill box of cross-section area S at the interface of two conductors.

The flux of 

According to Gauss Law

where σ  is the surface charge density at the interface

So, charge at the boundary of two conductors

The correct answer is: 

I = 1A
t = 1.6 second

⇒ q = It = 1 × 1.6 = 1.6
q = 1.6C
q = ne
n = number of electrons

The correct answer is: 10¹⁹

Total emf of the battery = 12 V
Total internal resistance of the battery = 3Ω

Current through battery (I) = 
Potential difference across battery  = emf of battery + Potential across the battery = 12 + (16 × 3)
= 60 V
The correct answer is: 60 V