Question
The rest mass of the photon is zero. Explain it.
✓
Answer
Planck believed that the emission of radiation energy or absorption is not continuous but in the form of discrete bundles. Photon is not a matter particle but it is a particle associated with radiation energy. It is also called quantum of energy. Photons are electrically neutral and their rest mass is zero.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
Using the formula for the radius of $n ^{\text {th }}$ orbit $r_n=\frac{n^2 h^2 \varepsilon_0}{\pi m e^2}$ derive an expression for the total energy of electron in $n^{\text {th }}$ Bohr's orbit.
→State the types of electric charge. Who coined these names?
Answer the following question:
A diver under water, looks obliquely at a fisherman standing on the bank of a lake. Would the fisherman look taller or shorter to the diver than what he actually is?
A diver under water, looks obliquely at a fisherman standing on the bank of a lake. Would the fisherman look taller or shorter to the diver than what he actually is?
Is it necessary for the plane of the orbit of a satellite to pass through the centre of the earth?
Two bar magnets are moving rapidly towards a metallic loop joined across a capacitor C as shown in the figure. What is the polarity of the capacitor?
Two metallic wires of the same material have the same length but cross-sectional areas are in the ratio 1 : 2. They are connected (i) in series and (ii) in parallel. Compare the drift velocities of electrons in the two wires in both the cases (i) and (ii).
Find the electric force between two protons separated by a distance of $1$ fermi $(1$ fermi $= 10^{-15}m).$ The protons in a nucleus remain at a separation of this order.
→A solid sphere of mass m is released from rest from the rim of a hemispherical cup so that it rolls along the surface. If the rim of the hemisphere is kept horizontal, find the normal force exerted by the cup on the ball when the ball reaches the bottom of the cup.
When the last image of the telescope is formed at infinity, then what is the length of its tube? If the image is formed at the minimum distance of clear vision then will the length be less or more than before?
Write formula for Bohr's orbit radius for hydrogen atom.