Important Questions (1 Mark): Electricity - UPSC MCQ

Time rate of work done or electric energy develop or consumed by generator or appliance, is called electric power. We know, that the rate of work done per unit Time is known as power. So, here is some change ie., in terms of electricity Time rate of work done is known as electric power. 

Firstly, you get shorter battery life simply because your average energy consumption is increased over the peak period.A battery generates power when it powers a light bulb. It dissipates power when it is being charged.

Power is directly proportional to the potential difference and potential difference is directly proportional to the Current. In a series combination, Resistance is increased and thus the flow of current decreases Power is directly proportional to current therefore power decreases.

As more and more resistors are added in parallel to a circuit, the equivalent resistance of the circuit decreases and the total current of the circuit increases.Therefore the power decreases.

Power  =  voltage * current
Here, power = 100 W, voltage = 200 V 
P  = V*I 
Therefore, 100  = 200  * I 
I   = 100/200 A
I   =  0.5 A

Energy is the ability to do work, where work is done when a force moves an object. We need and we use energy every day, and energy is available in all different forms. Electrical energy is energy that is stored in charged particles within an electric field. 

Joule is the unit of work or energy; it is equal to the work done by a force of one newton acting through one meter. It was named in honor of the English physicist James Prescott Joule. It equals 107 ergs, or approximately 0.7377 foot-pounds. In electrical terms, the joule equals one watt-second—i.e., the energy released in one second by a current of one ampere through a resistance of one ohm.

When electrons starts drifting into lower potential to higher potential then it get collision with their atoms. Due to which electron loses their kinetic energy and cause heat effect of current.

Energy = v × i × t = 6 × 0.5 × 20 = 60J

In domestic electric circuits, the cheapest appliance used is fuse bulb . 
An electric fuse is used as a safety device for the protection of electric circuits and appliances due to short - Circuiting or overloading of the electric circuits. 

20 Divisions are equal to the 2A
1 division is equal to 2/20 = 0.1 A
therefore Least count of the Ammeter is 0.1 A.

Least count L. C = 0.5 / No. of divisions 
Least count of voltmeter L. C = 0.5/20
 => 0.025 

We know that the voltmeter is always connected in parallel across the resistance to measure voltage across the resistance. So, option ( b) is the correct answer.

Resistance ‘R = 6ohm’ is related to length ‘L’, area of cross-section ‘A’ and resistivity ‘ρ’ as,

R = ρL/A

When L is doubled ,

As we know that the volume of the wire remains same.

old volume = new volume

AL = A'L' ....(i) ( as volume = area x length )

L' = 2L

So, from (i)

A' = A/2

So the new resistance is ,

R' = ρL'/A'

or

R' = ρ(2L)/(A/2) = 4 (ρL/A)

=> R' = 4R

thus, correct answer is option (b).

Electric pressure is also called as voltage or electrical potential. 1 volt is the amount of pressure required to flow one ampere of electricity through one ohm of resistance.
The difference in the electric potential between the two points is known as voltage. 

Electrically neutral atoms simply possess the same number of electrons as protons. This gives the object a balance of both type of charge.

Electrons have negative energy. When the number of electrons and protons are equal the charge is neutral but if electron is added to it then the negative charge dominates which gives it negative charge.