Test: Ohm's Law - UPSC MCQ

• The water heating rod has a resistance of 12 ohms and draws a current of 10 amps.
• To find the voltage, use Ohm's Law: Voltage = Current x Resistance.
• Substituting the values: Voltage = 10 A x 12 Ω = 120 V.
• Therefore, the source voltage is 120 V, which corresponds to option 2.
• This confirms that the correct answer is B.

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.

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.

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

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