Answer:
D. Light only
Explanation:
This is because photoelectric effect is a phenomenon in which electrically charged particles are emitted from a material when light is incident on it.
The light generates the energy which causes the material to emit electrons.
These electrons are only emitted at certain values of light energy, this thus shows that the light has to be quantized since electrons are not emitted over a range of values of light energy.
Thus, to fully describe the photoelectric effect, only light needs to be quantized.
Answer:
Explanation:
Given
Two block are connected by rope 
rope is attached to block 2
suppose
is a force applied to Rope
Applied force
=Tension in Rope 2

where a=acceleration of system
Tension in rope
is denoted by 

divide 1 and 2 we get

also 



Answer:
Net electric field, 
Explanation:
Given that,
Charge 1, 
Charge 2, 
distance, d = 3.2 cm = 0.032 m
Electric field due to charge 1 is given by :



Electric field due to charge 2 is given by :



The point charges have opposite charge. So, the net electric field is given by the sum of electric field due to both charges as :



So, the electric field strength at the midpoint between the two charges is 91406.24 N/C. Hence, this is the required solution.
I think it might be heat energy. light transforms into heat energy