TEN
PROBLEMS
1.
How much time is required for 25 x 10 ^18 electrons to leave the negative
terminal of the battery, if current provided by the batter is one amperes.
2.
Determine the potential energy of 12V battery that has 6000 coulombs of charge
stored in it.
3.
What is the power rating of an electric device that converts 1880 joules of
energy in 20 sec?
4.
How much energy is required to operate 100 W incandescent lamp for 30 minutes?
5.
An electric iron operates 220 V outlet draw 5 ampere current at rupees 2.25 per
kWh. How much does it cost to operate the iron for two hours?
6.
What is the efficiency of 0.75 hp motor that requires an input of 800 W of
electric power?
7.
A strip of aluminium has a length of 5 metre and cross section of 16 mm x 2.5
mm. find the resistance of the strip. Resistivity of aluminium is 2.83 x 10^-8
ohm-metre.
8.
A bread toaster has a Nichrome unit resistivity 112 x 10^-8 ohm-metre of
resistance 35 ohms. What is the resistance of copper conductor of equal area of
cross section but 10 times as long as the Nichrome wire. Resistivity = 1.7 x
10^-8 ohm-metre.
9. The field coil of a motor has a
resistance of 200 ohms at 15 degree centigrade. Find the resistance at 45
degree centigrade. Assume that the temperature coefficient as 0.00428 per
degree centigrade at zero degree centigrade.
10. An incandescent lamp takes 2.2 amps
at 220 V at the instant of switching it on. At the normal operating temperature
the current drops to 0.2 A. Find the temperature of the heated filament room
temperature is equal to 20 degree centigrade and the corresponding temperature
coefficient of the filament is 0.005 per degree centigrade.
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