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.

According to Ohm's Law, for a given metallic wire at constant temperature, voltage (V) is directly proportional to current (I). The straight-line graph passing through the origin indicates this linear relationship

Ohm's Law states that V = IR, meaning voltage is directly proportional to current, provided resistance remains constant.

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

The SI unit of resistance is Ohm (Ω), which represents how much a conductor resists the flow of electric current.

Ohm's Law states that the potential difference (V) across a conductor is equal to the current (I) multiplied by the resistance (R).

Using Ohm's Law, R = V/I. So, R = 1V/1A = 1Ω.

From Ohm's Law, I = V/R. If R is doubled, I decreases because they are inversely proportional.

Ohm's Law holds true only when the temperature of the conductor remains constant. If the temperature changes, the resistance of the material can also change, affecting the linear relationship between voltage and current.

The V-I graph for an ohmic conductor is a straight line that passes through the origin, showing a direct proportionality between voltage and current.