SOME NUMERICAL RELATED TO CURRENT ELECTRICITY:-

NUMERICAL (CURRENT ELECTRICITY)

1.If 0.5 mole of electrons flows through a wire in 8 minutes, find the magnitude of electric current?

2.If i = 3t2 + 2t. Calculate the quantity of charge that passes through a cross section of wire during the time t= 0sec to t = 3 sec.

3.In a hydrogen discharge tube , the number of protons drifting across a cross section per second is 1× 10^18, while the number of electrons drifting in the opposite direction across the same cross section is 2.7×10^18 per second. Find the current flowing in the tube.

4.The current density across a cylinder conductor of radius R varies in magnitude according to equation j =j'(1-r/R), where r is the distance from the central axis. Thus, the current density is maximum at j' at that axis(r= 0) & decreases linearly to 0 at the surface (r=R). Calculate the current in terms of j' & the conductors cross sectional area is A= πR2.

5.How much time will be taken by an electron to move distance l= 1 km in a copper wire of cross section A = 1mm2, current i = 0.8Amp.

6.Potential difference of 4.5 V is applied across a conductor of length 0.1m. if the drift velocity of electron is 1.5 × 10^-4 m/sec. Find electron mobility?

7.A wire of resistance 9 ohm is compressed to 1/3 of its length, find its new resistance?

8.A cylinder wire has length l & area of cross section A, the resistivity of wire changes as       ¶ = ¶°x, find the resistance of wire.

9.A copper coil has a resistance of 20 ohm at 0°c & a resistance of 26.4 ohm at 80°c. Find the temperature coefficient of resistance of copper coil?

10.The temperature coefficient of resistivity of copper is 0.004°c^-1, find the resistance of 5m long copper wire of diameter 0.2mm at 100°c if the resistivity of copper wire at 0°c is 1.7×10^-8 ohm meter.