#### Thank you for registering.

One of our academic counsellors will contact you within 1 working day.

Click to Chat

1800-5470-145

+91 7353221155

CART 0

• 0
MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping

# When the rest mass of photon become zero. Please explain this

Manas Shukla
102 Points
5 years ago
Photon has a rest mass of 0.
To understand the above statement we need to know what the term rest mass actually means.
Rest mass is the mass of the particle when measured by an observer who sees the particle still and with zero speed.
Now as we know light always travels with the speed c. So rest mass drops to 0 according to equation
$m = \frac{m_{0}}{\sqrt{1- \frac{v^{2}}{c^{2}}}}$.
Whereas Energy of photons can be calculated using einstein equation
$E^{2} = (mc^{2})^{2} + (pc)^{2}$
Photons dont have rest mass but they have energy and thus implying they have mass.
Thus photos dont have rest mass but have mass.