Question Details

The voltage across a lamp is (6.0± 0.1) volt and the current passing through it is (4.0± 0.2) ampere. Find the power consumed.

Options

A

(22.0± 1.6) watt

B

(23.0± 1.6) watt

C

(21.0± 1.6) watt

D

(24.0± 1.6) watt

Correct Answer :

(24.0± 1.6) watt

Solution :

The correct option is (24.0± 1.6) watt.

Step 1: Calculate the nominal power consumed.
The power P consumed by an electrical component is given by the formula:
P=V×I
where:
- Voltage, V=6.0 V
- Current, I=4.0 A

Substituting the nominal values into the equation:
P=6.0×4.0=24.0 watt

Step 2: Calculate the error in power.
For a product of two quantities, the relative error in the result is the sum of the relative errors of the individual quantities:
ΔPP=ΔVV+ΔII
where:
- Absolute error in voltage, ΔV=0.1 V
- Absolute error in current, ΔI=0.2 A

Substitute the values to find the fractional error in power:
ΔPP=0.16.0+0.24.0

Find a common denominator to sum the fractions:
ΔPP=160+240=160+120

ΔPP=1+360=460=115

Now, solve for the absolute error in power ΔP:
ΔP=P×115

ΔP=24.0×115=1.6 watt

Step 3: Express the final result with error limits.
Combining the nominal power and its absolute error:
Power=(P±ΔP)=(24.0±1.6) watt

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