Question

If an incident ray parallel to x-axis falls on the parabola or concave mirror, reflects through focus.

• A. True
• B. False

Answer 1

The correct option is A

True

In the previous question, we have already proved that SP=ST=SG

Let $\angle STP=\theta$

In $△PST$

PT=SP

$\angle STP=\angle SPT=\theta$ {angle opposite to equal sides are equal}

$\angle TPM=\angle STP=\theta$ {alternate angle}

$\Rightarrow \angle TPM=\angle STP=\angle SPT=\theta$

So,

PT bisects $\angle MPS$

$\angle MPT=\angle SPT$

If an incident ray (MP) parallel to x-axis falls on

concave mirror (Parabola $y^2=4ax$), it reflects through focus S(a,0).

Above given statement is correct.