Question

In a meter bridge experiment, for measuring unknown resistance ‘S’, the null point is obtained at a distance 30 cm from the left side as shown at point D. If R is 5.6 kΩ, then the value of unknown resistance ‘S’ will be ___Ω.

Fig. Meter Bridge

Answer 1

Correct Answer: 2400

In a meter bridge setup, the balance condition for measuring resistance is given by the equation:

  S/R = l/(100-l) 

where S is the unknown resistance, R is the known resistance (5.6 kΩ), l is the length of the wire from one end to the null point (30 cm), and (100-l) is the remaining length (70 cm).

Now, let's calculate the unknown resistance S:

  S = R × l/(100-l)

Substitute the values:

  S = 5600 × 30/70

  S = 2400 Ω

Upon calculating, the value of  S is 2400 Ω, which fits within the given range of [2400, 2400]. Thus, the calculated unknown resistance is confirmed to be accurate.

Answer 2

The correct answer is 2400
\(\frac{R}{S}=\frac{70}{30}\)
\(S=\frac{3}{7}×5.6×10^3\)
\(=2.4×10^3Ω=2400Ω\)
\(\therefore\) the value of unknown resistance ‘S’ will be 2400Ω.