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A 60-W lightbulb operates on a 120-V source. What is the current flowing through the bulb?
0.5 A
1 A
2 A
5 A
0.5 A
The current flowing through a lightbulb can be calculated using the power formula relating electrical power, voltage, and current. Given a power of 60 W and a voltage of 120 V, the current is found by dividing power by voltage.
The current flowing through a lightbulb can be calculated using the power formula relating electrical power, voltage, and current. Given a power of 60 W and a voltage of 120 V, the current is found by dividing power by voltage.
Think of voltage as the water pressure in a pipe and current as the flow rate of water; if you have a fixed power capacity, higher pressure allows you to achieve the same work with less water flow.
Remember 'PIV' (Power = Current ├ЧVoltage) to easily rearrange the variables for any unknown value.
P=V├ЧI тАФ Relation between power, voltage, and current
I=VPтАЛ тАФ Derivation for calculating current
According to the principle of electrical power, the rate at which electrical energy is dissipated by a resistor is P=V├ЧI. By rearranging this formula to solve for current, we get I=VPтАЛ. Substituting the given values: I=120┬аV60┬аWтАЛ=0.5┬аA.
Electrical power (P) is measured in Watts (W).
Voltage (V) is measured in Volts (V).
Current (I) is measured in Amperes (A).
The relationship holds true for purely resistive loads like incandescent bulbs.
Simple relationship for quick calculations in electrical engineering problems.
Assumes a purely resistive load and ignores power factor in AC circuits.
Calculating current ratings for household appliance fuses.
Designing circuit breakers for home electrical wiring.
Standard household supply voltage in India is 220 V, but this problem specifies a 120 V source.
Option B (1 A) would occur if the power were 120 W. Option C (2 A) would occur if the power were 240 W. Option D (1.5 A) would occur if the power were 180 W.
A is correct тАФ The current is calculated as I=12060тАЛ=0.5 A.
Always verify units before calculating; if power was in kW, convert to W first to match the Voltage (V) and Current (A) units.
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