Question

On average, a 3-V spotlight draws 0.25 A of current and generates a cylindrical beam of visible light that has an area of 5 cm2. What is the average intensity of the beam? O 0.25 W/square meter O 0.75 W/square meter O 250 W/square meter O 750 W/square meter O 1500 W/square meter

Answer 1

As we know that the power of that spot light is given as

P=I.V

So, P=0.25×3=0.75

And we know that the intensity is given by

I=P/A. Where, P is power and A is area

So, I=0.75/5×10^(-4). {1m^2=10^(-4)cm^2}

I=1500 W/square metres.