Choose the correct alternative (a), (b), (c) or (d):

• ∈₀= 9∈_w 
• ∈₀=81∈_w
• ∈_w=9∈₀ 
• ∈_w=81∈_o 

Five resistors are connected as shown in Figure 1. 



The effective resistance i.e. equivalent resistance between the points A and B is:

• 4Ω 
• 5Ω
• 20Ω   
• 20Ω

A large hollow metallic sphere has a positive charge of 35.4μC at its centre. Find how much electric flux emanates from the sphere.

A current T flows through a metallic wire of radius ‘r’ and the free electrons in it drift with a velocity v_d. Calculate the drift velocity of the free electrons through the wire of the same material, having double the radius, when same current flows through it.

Current flowing through the conductor, i - neAV_d
Therefore,

Drift velocity, v_d = 
r' = 2r