A current of `2.50` A passing through a heating coil immersed in `180 g` of paraffin (specific heat capacity `2.00 J g^(-1) K^(-1)`) contained in a `100 g` calorimeter (specific heat capacity `0.400 J g^(-1) K^(-1)`) raise the temperature from `5^(@)C` below room temperature to `5^(@)C` above room temperature in `100 s`. the reading of the voltmeter connected across the heating coil is

Options

A. `8.0 V`
B. `16.0 V`
C. `24.0 V`
D. `32.0 V`

Answer

B

Explanation

Power `= ("heat supplied")/("Time")`
`=(m_(1)s_(1)Delta theta+m_(2)s_(2)Delta theta)/(T)`
`(180g xx 2 Jg^(-1)K^(-1)xx10K)+`
`=((100gxx0.4Jg^(-1)K^(-1)xx10K))/(100s)`
`=40W`
`=VI = 40 W rArr V = (4.0)/(2.5) = 16.0V`.