Question 471: Current Electricity

Question

The energy dissipated by a resistor is 10 mJ in 1 s when an electric current of 2 mA flows through it. The resistance is ___________$$\Omega$$. (Round off to the Nearest Integer)

Accepted Answer

Given, energy dissipated by a resistor, H = 10 mJ = 10 $$	imes$$ 10
$$-$$3
J
Time, t = 1 s
Electric current, I = 2 mA = 2 $$	imes$$ 10
$$-$$3
A
Resistance, R = ?
According to Joule's law of heating,
H = I
2
Rt
$$ \Rightarrow R = {H \over {{I^2}T}}$$ ....... (i)
Substituting the given values in Eq. (i), we get
$$R = {{10 	imes {{10}^{ - 3}}} \over {{{(2 	imes {{10}^{ - 3}})}^2} 	imes 1}}$$
$$ \Rightarrow R = {{{{10}^{ - 2}}} \over {4 	imes {{10}^{ - 6}}}} \Rightarrow R = 0.25 	imes {10^4}$$
$$ \Rightarrow R = 2500\,\Omega $$

Current Electricity

The energy dissipated by a resistor is 10 mJ in 1 s when an electric current of 2 mA flows through it. The resistance is ___________$\Omega$. (Round off to the Nearest Integer)

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