Q83.

Expert-verifiedFound in: Page 454

Book edition
4th

Author(s)
Randall D. Knight

Pages
1240 pages

ISBN
9780133942651

A communications truck with a 44-cm-diameter dish receiver on the roof starts out 10 km from its base station. It drives directly away from the base station at 50 km/h for 1.0 h, keeping the receiver pointed at the base station. The base station antenna broadcasts continuously with 2.5 kW of power, radiated uniformly in all directions. How much electromagnetic energy does the truck’s dish receive during that 1.0 h?

0.000181J

radius of dish(r): 44/2 cm= 0.22m

v = 50km/h = 50000m/h = 13.88m/s

Time = 1hr

Energy received by dish is power received over the course of 1hr time period.

____ eq (1)

Now, Intensity received by dish is ,

Where, P = power

A = Area

So, P = IA

____ eq(3)

Now we know that the truck is moving away from the station at a constant speed. So truck's distance from station at any time t is

Substituting this in equation 3 we get,

Here A =

Substituting this value in above equation we get:

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