i) Three resistors 2 Ω, 4 Ω and 5 Ω are combined in parallel. What is the total resistance of the combination?

ii)If the combination is connected to a battery of emf 20 V and negligible internal resistance, determine the current through each resistor, and the total current drawn from the battery.

Total resistance of parallel combination,

or
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At room temperature (27.0 °C) the resistance of a heating element is 100 Ω. What is the temperature of the element if the resistance is found to be 117 Ω, given that the temperature co-efficient of the material of the resistor is 1.70 x 10–4°C–1.

Given,
Resistance of the element,
Resistance of heating element at room temperature,
Temperature coeffient of the material of resistor,$\mathrm{\alpha }$=1.70 x 10–4°C–1

Now, using the relation

we get,

is the required temperature of the element.

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A battery of emf 10 V and internal resistance 3 Ω is connected to a resistor. If the current in the circuit is 0.5 A, what is the resistance of the resistor? What is the terminal voltage of the battery when the circuit is closed?

Given,
EMF of battery,
Internal resistance of battery, r=
Current flowing in the circuit, I= 0.5 A

Using the forlmula

or
where, R is the external resistance.
$\mathbf{\therefore }$ is the required resistance.

Terminal voltage,

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# The storage battery of a car has an emf of 12 V. If the internal resistance of the battery is 0.4 Ω , what is the maximum current that can be drawn from the battery?

Maximum current is drawn from a battery whenthe external resistance in the circuit is zeroi.e., R = 0.

Given,
E.m.f of the battery,
Internal resistamce of the battery,
Therefore, using the formula for maximum current drawn we get,
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a) Three resistors 1 Ω, 2Ω, and 3 Ω are combined in series. What is the total resistance of the combination?
b)If the combination is connected to a battery of EMF 12 V and negligible internal resistance, obtain the potential drop across each resistor.

Resistance of series combination

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