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dimulka [17.4K]
3 years ago
9

A point source emits electromagnetic energy at a rate of 100 W. The intensity 10 m from the source is

Physics
1 answer:
MariettaO [177]3 years ago
5 0

Answer:

I=0.0795\ W/m^2

Explanation:

Given that,

Power of electromagnetic energy, P = 100 W

We need to find the intensity at a distance of 10 m from the source. Intensity is equal to the power per unit area. So,

I=\dfrac{P}{4\pi r^2}\\\\I=\dfrac{100}{4\pi (10)^2}\\\\I=0.0795\ W/m^2

So, the intensity at a distance of 10 m is 0.0795\ W/m^2

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Nitrogen at 100 kPa and 25oC in a rigid vessel is heated until its pressure is 300 kPa. Calculate (a) the work done and (b) the
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Answer:

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B. The value of heat transfer during the process Q = 442.83 \frac{KJ}{kg}

Explanation:

Given Data

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Initial temperature T_{1} = 25 degree Celsius = 298 Kelvin

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Vessel is rigid so change in volume of the gas is zero. so that initial volume is equal to final volume.

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Since volume of the gas is constant so pressure of the gas is directly proportional to the temperature of the gas.

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⇒ T_{2} = 894 Kelvin

(A). Work done during the process is given by W = P × (V_{2} -V _{1})

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Heat transfer during the process is given by the formula Q = m C_{v} ( T_{2} -T_{1} )

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Thus the heat transfer Q = 1 × 0.743 × ( 894- 298 )

⇒ Q = 442.83 \frac{KJ}{kg}

Therefore the value of heat transfer during the process Q = 442.83 \frac{KJ}{kg}

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