A photoelectric cell is an electronic device which is used to convert light energy into electric energy.The operation of this device is based on photoelectric effect.
Light of suitable frequency i.e greater or equal to threshold frequency will fall on the cathode maintained at negative potential.The electron emission will take place and these electrons are drifted towards the anode which is at positive potential.
Here,only those radiations will be capable of emitting electrons irrespective of surface barrier of metals whose energy is greater than the work function.
We know that the radiation having long wavelength has least energy as energy and wavelength are inversely proportional to each other.

Here h is the Planck's constant,c is the velocity of light.
Here we have been given red light and blue light.
In the visible spectrum of radiation, the red light has longer wavelength than all other colors of light.Hence blue light has more energy as it's wavelength is less as compared to red light.
Hence, the blue light will activate the most and red the least.
Answer:
90.9 seconds
Explanation:
m = Mass of liquid = Volume×Density
c = Specific heat
= Change in temperature
t = Time taken
Room temperature = 75 °F
Converting to Celsius

Heat required to raise the temperature of water

Power

Efficiency of the plate

Heat required to raise the temperature of water


Time taken to heat the aceton is 90.9 seconds
This phenomena is referred to as metal projectile injury/effect. MRI stands for magnetic resonance imaging. As expected, your body is subjected to a magnetic field. This is a technique to look inside your body without cutting it open. Metals should not be placed anywhere near an MRI because it will cause the metals to follow the direction of the magnetic field.
PART A)
horizontal distance that will be moved = 14 m
Height of the fence = 5.0 m
height from which it is thrown = 1.60 m
angle of projection = 54 degree
So here we can say that stone will travel vertically up by distance

now we will have displacement in horizontal direction

now we know that


now we will have


also for y direction


now from the two equations we will have




now from above equations


So the minimum speed will be 13.2 m/s
Part B)
Total time of the motion after which it will land on the ground will be "t"
so its vertical displacement will be

now we will have




Now the time after which it will reach the fence will be t1 = 1.8 s
so total time after which it will fall on other side of fence


now the displacement on the other side is given as



Answer:
The energy of the system is 15 J.
Explanation:
Given that,
Energy E = 2.5 J
Amplitude = 10 cm
We need to calculate the spring constant
Using formula of mechanical energy of the system

Put the value into the formula



If the block is replaced by a block with twice the mass of the original block
Amplitude = 6 cm
We need to calculate the energy
Using formula of mechanical energy

Put the value into the formula


Hence, The energy of the system is 15 J.