In the circuit shown, when keys K1 and K2 both are closed, the ammeter reads I0. But when K1 is open and K2 is…..

Q. In the circuit shown, when keys K1 and K2 both are closed, the ammeter reads I0. But when K1 is open and K2 is closed the ammeter reads I0/2. Assuming that ammeter resistance is much less than R2, the values of r and R1 in Ω  are

Current Electricity

(a) 25, 50

(b) 25, 100

(c) 0, 100

(d) 0, 50

Ans: (d)

A battery of emf E0 = 12V is connected across a 4m long uniform wire having resistance 4Ω/m. The cell of small emfs…..

Q. A battery of emf E0 = 12V is connected across a 4m long uniform wire having resistance 4Ω/m. The cell of small emfs e1 = 2V and e2 = 4V having internal resistance 2Ω and 6Ω respectively are connected as shown in the figure. If galvanometer shows no deflection at the point N, the distance of point N from the point A is equal to

Current Electricity
(a) 5/3 m
(b) 4/3 m
(c) 3/2 m
(d) None of these

Ans: (d)

Two wires A and B made of same material and having their lengths in the ratio 6 : 1 are connected in series…..

Q. Two wires A and B made of same material and having their lengths in the ratio 6 : 1 are connected in series. The potential difference across the wires are 3V and 2V respectively. If rA and rB are the radii of A and B respectively, then rB /ris

(a)  1/4

(b) 1/2

(c)    1

(d) 2

Ans: (b)