The current through a certain heater wire is found to be fairly independent of its temperature. If the current through the heater wire is doubled, the amount of energy delivered by the heater in a given time interval will .a) increase by a factor of two.. b) decrease by a factor of two.. c) increase by a factor of four. d) decrease by a factor of four e) increase by a factor of eight

Explanation:

If the initial current is i,

The energy delivered by the heater is given as

Hi=i²Rt

Then, when the current is double

So the new current is 2i

So the heat delivered will be

Hn=(2i)²Rt

Hn=4i²Rt

Hn=4•i²Rt , i²Rt =Hi

Hn=4•Hi

Notice that the resistance of the heater doesn't change.

And the time will not change since we are considering the same time intervals (t)

Conclusion, it is notice that the amount of heat delivered by the heater when the current was double, increase the heat delivered by a factor of 4.

So the correct answer is C

a solenoid is created by wrapping a l = 90 m long wire around a hollow tube of diameter d = 4.5 cm.   the wire diameter is d = 0.9 mm.   the solenoid wire is then connected to a power supply so that a current of i = 9 a flows through the wire.

randomized variablesl = 90 m

d = 4.5 cm

d = 0.9 mm

i = 9 a                                          

write an expression for the number of turns, n, in the solenoid. you do not need to take into account the diameter of the wire in this calculation.

calculate the number of turns, n, in the solenoid.

write an expression for the length of the solenoid (l2) in terms of the diameter of the hollow tube d.

calculate the length of the solenoid (l2)   in meters.

calculate the magnitude of the magnetic field at the center of the solenoid in teslas.

explanation: