Question

"The expression of current through a metal is given by I = nqvdA, if the temperature increases what happen?"

		I decreases
		I increases
		I remains same
		n changes

What is the unit of Potential difference (V) times Current (I)?

		Energy
		Torque
		Power
		Force

If the temperature of a metal increases the resistivity will

		change
		decrease
		Increase
		No change

VV

In a parallel connection of resistance the voltage will be

		Increase
		Decrease
		Split
		Same

Answer 1

Answer 1: I decreases

Explanation: I = nqv_d A

where, n = no of free electrons in unit density of the conductor , q = charge of each electron , v_d = drift velocity of the free electrons inside the conductor , and A = cross sectional area of the conuctor.

When the temperature of the conductor is increased , atoms of the metal get excited and start vibrating. These vibrating atoms block the path for free electrons to flow. As a result, the drift velocity (v_d) of the electrons is decreased , which results in decreased I , since I is directly proportional to v_d.

Answer 2: Unit of Potential difference (V) times Current (I) is Power

Explanation:

Potential difference (V) between two points A and B = work done to transfer unit positive charge from A to B.

So, if +Q charge is transferred from point A to point B , the work done in the process (W) will be equal to V*Q

Or, V*Q = W

Or, V*Q/t = W/t [ here t = time duration of the process ]

Or, V*I = Power [ (Q/time) = charge flow rate = current I,   and ( work / time)= rate of doing work = power]

Answer 3 : If the temperature of a metal increases, the resistivity will increase.

Explanation:

Resistivity is the property of a material to resist flow of electrons through itself. Since at increased temperature atoms of the metal will be vibrating more, the drift velocity of the free electrons will get slower as they will be colliding with the vibrating atoms more frequently. Thus, the resistivity of the metal will increase.

Answer 4: In parallel connection of resistor the voltage will be same.

Explanation: In parallel connection all the resistors are connected to same voltage difference independently. Therefore, voltage drop across one resistor doesnot affect another and the voltage remains same for all the resistors. However, the currents flowing through different resistors are different.