A 100-watt light bulb radiates energy at a rate of 100 J/s. (The watt, a unit of power or energy over time, is defined as 1 J/s.) If all of the light emitted has a wavelength of 525nm, how many photons are emitted per second?

photons are emitted per second.

Explanation:

Let the number of photons emitted by bulb be 'n'.

Given:

Energy radiated by bulb per second (E) = 100 J

Wavelength of light emitted (λ) = 525 nm =

We know that,

Energy of a photon is given as:

Where,

Now, if there are 'n' photons, the energy will be equal to energy of 1 photon times the number of photons. So,

Now, rewriting in terms of 'n', we get:

Plug in the values given and solve for 'n'. This gives,

Therefore, photons are emitted per second.

can be answered using momentum.

momentum = p

p1= mass1 * velocity1

p1 = p2

therefore

p1 = 6kg * 4m/s

p1 = 24kgm/s

p2=m2 * v2

24 kgm/s = 7kg * v2

v2 = 24 kgm/s / 7kg

v2= 3.42 m/s

we need to know the time interval during which the force acts. impulse of force = momentum change