Intensity

Q.

Consider the earlier problem where we had a point source radiating energy at the rate of 10 Joules per second, or 10 Watts. What can you say about the intensities $I_{1}and{I}_2$ at two points on spheres of radii and $r_{1}and{r}_2$ respectively, centered at the source?

1. $I_1=I_2$

2. $I_1{r}_1=I_2{r}_2$

3. $I_1{r}_1^2=I_2{r}_2^2$

4. $I_1{r}_2^2=I_2{r}_1^2$

Q.

Which of these light sources will have a cylindrical wave front?

1. Point source

2. Infinite Line source

3. Plane source

4. Spherical source

Q.

2 planets 'Xargonia' and 'Olfuba' have taken keen interest in our star 'The Sun'. They are observing our sun from the observatories built on their planet.

Xargonia is 1 Light year away and the aperture area of its telescope is $1m^2$, while Olfuba is 2 Light years away and the aperture area of its telescope is $4m^2$.

Find out whose telescope receives more energy? (Assume the Sun radiates E joules of energy per sec.)

1. Xargonia

2. Olfuba

3. Both receive equal

4. Data insufficient