(a) Name a device which is used to : (i) Maintain a constant potential difference in a circuit. (ii) Change…
(a) Name a device which is used to :
(i) Maintain a constant potential difference in a circuit.
(ii) Change the electric current in an electric circuit.
(b) When the potential difference between the terminals of an electric heater is 110 V, a current of 5 A flows through it. What will be the value of current flowing through it when the potential difference is increased to 220 V ?
Solution
(a) (i) Battery / Electric cell
(ii) Rheostat / Variable resistance
V
(b) Resistance of the heater, R =
I
R=
R = 22
V′
Current through the heater, I′ =
R
=
= 10 A
/
Alternate answer for (b):
• According to Ohm’s law, potential difference is directly
proportional to current.
• When the potential difference is doubled, current will also be
doubled. So, value of current will be 10A.