MODEL TEST ON LIGHT

If an object is placed at a distance of 20 cm the image falls on 2F₁ , then the focal length of the lens is

• 10 cm

• 15 cm

• 20 cm

• 40 cm

In which substance is the speed of the light is more

• vaccum

• air

• water

• diamond

Critical angle is the angle of _____

• refraction

• reflection

• incidence

• none of the above

The full form of TIR IS

• Total internal refraction

• To the internal reflection

• Total in reflection

• Total internal reflection

Here are some substances given , which is having the high refractive index

• Ruby

• diomand

• crown glass

• air

When an object is placed at infinite before the double convex lens image falls at

• center of curvature

• at infinite

• on focus

• image does't fall

1/f = 1/v - //u by using this formula we can find

• focal length

• object distance

• image distance

• all the above

1/f = (n-1) ( 1/R₁ -1/R₂) in this formula 'n' represents the ___

• refractive index of the material

• focal length of the lens

• center of curvature of the lens

• radius of curvature of the lens

Which one of the following is a convergent lens

• double concave

• plano concave

• double convex

• none of the above

What are the S.I units of refractive index

• cm/s

• Nm²

• m/s²

• no units