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The below circuit is a part of an electrical device. Use the information given in the question to calculate the following.

The below circuit is a part of an electrical device. Use the information given in the question to calculate the following. CBSE 2024 Science Class 10 Sample Question Paper Solved.

(a) Potential Difference across R2.

(b) Value of the resistance R2.

(c) Value of resistance R1.

Current Electricity

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Answer

From the diagram,

  • Voltage of battery (V) = 12 V
  • Net current through the circuit (I) = 2.0 A
  • Current through 4 Ω resistor (i) = 1.5 A

(a) As, 4 Ω and R2 are in parallel then the potential difference across them should be equal i.e.,

Potential difference across R2 = Potential difference across 4 Ω

= i x 4

= 1.5 x 4

= 6.0 V

Hence, the potential Difference across R2 is 6.0 V.

(b) Now,

Current through R2 = I - i = 2.0 - 1.5 = 0.5 A

Then,

Potential difference across R2 = (I - i) x R2

⇒ (I - i) x R2 = 6

⇒ 0.5 x R2 = 6

⇒ R2 = 60.5=605\dfrac{6}{0.5} = \dfrac{60}{5}

⇒ R2 = 12 Ω

Hence, value of the resistance R2 is 12 Ω.

(c) As,

Potential drop across all series resistor = V

⇒ Potential drop across R1 + Potential drop across R2 + Potential drop across 2.0 Ω = 12

⇒ I x R1 + 6 + I x 2 = 12

⇒ 2 x R1 + 2 x 2 = 12 - 6

⇒ 2 x R1 + 4 = 6

⇒ 2 x R1 = 6 - 4

⇒ 2 x R1 = 2

⇒ R1 = 22\dfrac {2}{2}

⇒ R1 = 1 Ω

Hence, value of resistance R1 is 1 Ω.

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