In an electrical circuit, the voltage is measured as volt and the current is measured as A. The value of the resistance is:
- A
- B
- C
- D
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Correct answer: B
To determine the resistance $R$ using Ohm's law, we use the formula:
$R = \frac{V}{I}$
Given:
$V = (200 \pm 4)$ volts
$I = (20 \pm 0.2)$ amperes
First, calculate the nominal value of the resistance:
$$R = \frac{200}{20} = 10 \, \Omega$$
Next, we need to calculate the uncertainty in the resistance. For division, the relative uncertainties add up. The relative uncertainty for voltage is:
$$\frac{\Delta V}{V} = \frac{4}{200} = 0.02$$
and for current:
$$\frac{\Delta I}{I} = \frac{0.2}{20} = 0.01$$
Adding these relative uncertainties gives us the relative uncertainty for the resistance:
$$\frac{\Delta R}{R} = \frac{\Delta V}{V} + \frac{\Delta I}{I} = 0.02 + 0.01 = 0.03$$
Now, we calculate the absolute uncertainty for the resistance:
$$\Delta R = R \times 0.03 = 10 \times 0.03 = 0.3 \, \Omega$$
Therefore, the resistance with its uncertainty is:
$$R = 10 \pm 0.3 \, \Omega$$
Thus, the correct answer is:
Option B $(10 \pm 0.3) \Omega$
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