Electric Circuits Answers

A magnetic field is applied to the plain of a flat coil of copper wire. The time variation of the magnetic flux density is given by Bosinωt. At which of the following values of t is the magnitude of the emf induced in the coil a maximum?

a. T/8
b. 3T/8
c. 3T/4
d. T/2

A 0.96H coil carries a current of 8.0A. Calculate the energy stored in it

a. 30.7J
b. 45.3J
c. 62.6J
d. 27.3J

A rod of 5.0m length is held horizontally and with its axis in an east-west direction. It is allowed to fall straight down. What is the emf induced in it when its speed is 3.0m/s if the earth's magnetic field is
0.60×10^−4 T with a dip angle of 53 degrees?

a. 5.4×10^−4V
b. 3.6×10^−3V
c. 2.0×10^−5V
c. 4.2×10^−4V

The strength of the field at a distance of one meter from a long straight wire carrying a current of one ampere is 2×10^7

a. ampere-meter
b. Gauss
c. Tesla
d. volt per meter

An emf of 5V is suddenly applied to an LR circuit. The value of the resistor in the circuit is 15Ω. At one inductive time constant, what is the rate at which energy is delivered by the battery?

a. 1.05W
b.5.78W
c.120.42W
d.12.24W

What is the self - inductance of an air-core solenoid, 1m long and 0.05m in diameter, if it has 1400 turns?

a. 5.23mH
b. 4.84mH
c. 3.63mH
d. 2.42mH

An ammeter is suspected of giving inaccurate readings. In order to confirm the readings, the ammeter is connected to a silver voltmeter in series and a steady current is passed for one hour. The ammeter reads 0.56A and 2.0124g of silver is deposited.

a. 0.06A
b. 0.11A
c. 1.1A
d. 6.0A

For how long must a steady current of 2A flow through a copper voltmeter to deposit 10^−3kg of copper? Z for copper is 0.000329g/C

a. 42.1min
b. 22.6min
c. 30.2min
d. 25.3min

An electron enters a uniform magnetic field 0.20T at an angle of 30 degrees the field. Determine the pitch of the helical path assuming its speed is 3×10^7m/s

a. 90.6m
b. 37.8m
c. 56.1m
d. 46.5m