In a barber's shop, two plane mirrors are placed:

1. perpendicular to each other
2. parallel to each other
3. at an angle of 60° between them
4. at an angle of 45° between them.

For two mirrors kept parallel to each other, the number of images formed is :

1. 5
2. 7
3. 0
4. infinity

A thick plane mirror, silvered at its back, forms multiple number of images. Out of these, the brightest image is :

1. first image
2. second image
3. third image
4. All are of equal brightness

How many plane mirrors are used in a periscope and kaleidoscope ?

1. 2 and 3 respectively
2. 3 each
3. 3 and 2 respectively
4. 2 and 4 respectively