Electricity Worksheet-3
-
A conductor carries a current of 0.2 A. Find the amount of charge that will pass through the cross-section of the conductor in 30 s. How many electrons will flow in this time interval if the charge on one electron is 1.6 × 10–19 C ?
-
The filament of an electric lamp draws a current of 0.4 A which lights for 3 hours. Calculate the amount of charge that flows through the circuit.
-
An electric iron draws a current of 0.5 A when voltage is 200 V. Calculate the amount of charge flowing through it in one hour.
-
N electrons flow through a cross-section of a conductor in time t. if the charge on an electron is e, write an expression for the current in the conductor.
-
0.5 C charge passes through a cross-section of a conductor in 5 s. Find the current.
-
A polythene piece rubbed with wool is found to have negative charge of 3 × 10–7 C. Estimate the number of electrons transferred.
-
Calculate the current in a wire if 1500 C charge is passed through it in 5 minutes.
-
A current of 0.5 A is drawn by a filament of an electric bulb for 10 minutes. Find the amount of electric charge that flows through the electric circuit.
-
Calculate the amount of work done to carry 4C of charge from a point at 100 V to a point at 120 V.
-
What is the resistance of an electric arc lamp when hot, if the lamp uses 20 A when connected to a 220 volt line?
Answer:
-
Current I = 0.2A and time, t = 30 s
∴ charge, Q = I × t = 0.2 × 30 = 6 C
If n electrons flow and e is the charge on an electron, then
Q = ne so
-
current, I = 0.4 A and time t = 3 hours = 3 × 60 × 60 = 10800s
∴ charge, Q = I × t = 0.4 × 10800 = 4320 C
-
current I = 0.5 A and time, t = 1 hour = 60 × 60s = 3600 s
∴ charge, Q = I × t = 3600 × 0.5 = 1800 C
-
-
-
As Q = ne,
-
-
Q = It = 0.5 A × (10 × 60)s = 300 C
-
Potential difference between two points, V = 120 V – 100 V = 20 V
Charge to be moved, Q = 4 C
If W is the amount of work done, then
W = Q × V = 4 × 20 = 80 J
-
Potential difference across the arc lamp, V = 220 V
Current through the lamp, I = 20 A
∴ resistance of the lamp,