1.

Physics

2 answers:

gladu [14]4 years ago

6 0

When it has rained for 20 minutes

cricket20 [7]4 years ago

5 0

When driving in rain, the road becomes the most slippery <em>right after it starts to rain</em>.

As the first rainwater hits the road, it mixes with the oil, rubber tire particles, and other gunk on the pavement, forming a very slippery coating on the surface.

After it has rained for a while, a lot of that gunk gets washed away, and most of the slipperiness is just water ... which is pretty slippery on its own, but not as slippery as it is when it has oil and rubber particles in it too.

You might be interested in

What condition is necessary for the sustained flow of water in a pipe?

lianna [129]

Pressure difference (voltage)
<span />

5 0

4 years ago

The maximum wavelength an electromagnetic wave can have and still eject an electron from a copper surface is 264 nm .What is the

Tamiku [17]

Answer:

4.71 eV

Explanation:

For an electromagnetic wave with wavelength

$\lambda=264 nm = 2.64\cdot 10^{-7} m$

the energy of the photons in the wave is given by

$E=\frac{hc}{\lambda}=\frac{(6.63\cdot 10^{-34}Js)(3\cdot 10^8 m/s)}{2.64\cdot 10^{-7}m}=7.53\cdot 10^{-19} J$

where h is the Planck constant and c the speed of light. Therefore, this is the minimum energy that a photon should have in order to extract a photoelectron from the copper surface.

The work function of a metal is the minimum energy required by the incident light in order to extract photoelectrons from the metal's surface. Therefore, the work function corresponds to the energy we found previously. By converting it into electronvolts, we find:

$E=\frac{7.53\cdot 10^{-19} J}{1.6\cdot 10^{-19} J/eV}=4.71 eV$