# Test: Ohm's Law

## 5 Questions MCQ Test Science & Technology for UPSC CSE | Test: Ohm's Law

Description
Attempt Test: Ohm's Law | 5 questions in 10 minutes | Mock test for Class 10 preparation | Free important questions MCQ to study Science & Technology for UPSC CSE for Class 10 Exam | Download free PDF with solutions
QUESTION: 1

### The water heating rod draws 10 A current when connected to certain power source. The resistance of rod is 12 Ω. The source voltage is:

Solution:

The correct answer is B as Ohm's law:
voltage=current x resistance=12x10=120 V

QUESTION: 2

### Which method can be used for absolute measurement of resistances ?

Solution:

A Wheatstone bridge is an electrical circuit used to measure an unknown electrical resistance by balancing two legs of a bridge circuit, one leg of which includes the unknown component. The primary benefit of the circuit is its ability to provide extremely accurate measurements.

QUESTION: 3

### Electric current always flows

Solution:

Electrons move from low potential to high potential. The direction of electric current is opposite to the direction of flow of electrons.

Hence Electric current always flows from higher to lower potential.

QUESTION: 4

What is the kilowatt-hour consumption of a 40 W lamp if it remains on for 1750 h ?

Solution:

(1,750 x 40)/1000 = 70 kilowatt-hour.

QUESTION: 5

The potential difference of a circuit is constant. If the resistance of a circuit is doubled, then its current will become;

Solution:

According to ohm's law

Current (I) = Potential difference (V) / Resistance(R)

If the potential difference is maintained constant and the resistance is changed,

Cureent (I) is inversely proportinal to the reisistance (R)

V = IR                     --(1)

Now, here V is constant.

Let , new resistance R' = 2R and assume that current flow be I'

So, from (1),

IR = I'. R',

=> IR = I'. 2R,

Therefore, I' = I / 2

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