Physics, 22.11.2019 06:31 jvsome8

Ametal foil has a threshold frequency of 5.45×1014 hz . which of the colors of visible light have enough energy to eject electrons from this metal?

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Answer from: lnbrown5633

Green, blue, indigo and violet.

Explanation:

The velocity of a wave is given by

$v=f\lambda$

where

f = Frequency = $5.45\times 10^{14}\ Hz$

$\lambda$ = Wavelength

$\lambda=\frac{v}{f}\\\Rightarrow \lambda=\frac{3\times 10^8}{5.45\times 10^{14}}\\\Rightarrow \lambda=5.50459\times 10^{-7}\ m=550.459\times 10^{-9}\ m\\ =550.459\ nm$

The wavelength of the wave is 550.459 nm

Green light has wavelength which ranges from 500-565 nm.

So, the light which observed is green light and lower in wavelength than green light i.e., green, blue, indigo and violet.

Answer from: Quest

force is based upon mass and acceleration.the statement is not always true.

it can be explained from newton's second law of motion.

as per newton's second law of motion the rate of change of momentum is directly proportional to the applied force and takes place along the direction of force.

mathematically it can be written as -

$f\alpha \frac{dp}{dt}$

⇒ $f= k \frac{dp}{dt}$

here k is the proportionality constant whose value is 1.

$f=\frac{dp}{dt}$

$f= \frac{d[mv]}{dt}$

$f= m\frac{dv}{dt} +v\frac{dm}{dt}$

$f=ma+v\frac{dm}{dt}$ [a is the acceleration=dv/dt]

hence we see that force not only depends on mass and acceleration but also on velocity and rate of change of mass. force f will depend on mass and acceleration only when mass is constant.

hence the statement that force is based upon mass and acceleration is false.

Answer from: Quest

Ithink it’s: light bounce if off a mirror

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Ametal foil has a threshold frequency of 5.45×1014 hz . which of the colors of visible light have en...