Answer:
an electromagnetic wave with a wavelength in the range 0.001–0.3 m, shorter than that of a normal radio wave but longer than those of infrared radiation. Microwaves are used in radar, in communications, and for heating in microwave ovens and in various industrial processes.
Answer:
Potential energy
Kinetic energy
Gravitational energy.
Explanation:
The potential energy is the stored energy, it is the energy and object posses at rest. When the base jumper is still at rest i.e without motion, she has potential energy.
Gravitational energy this refer to the potential energy an object or body with mass posses in relation to another object due to gravity.
This is seen when the base number is still at rest and the force of gravity on the Earth acting on her.
Kinetic energy is the energy posses by an object or body in motion.
As the base jumper falls to the ground, she posses kinetic energy which is the energy in motion.
Answer:
The work function ϕ of the metal = 53.4196 x 10⁻¹⁶ J
Explanation:
When light is incident on a photoelectric material like metal, photoelectrons are emitted from the surface of the metal. This process is called photoelectric effect.
The relationship between the maximum kinetic energy () of the photoelectrons to the frequency of the absorbed photons (f) and the threshold frequency (f₀) of the photoemissive metal surface is:
= h(f − f₀)
= hf - hf₀
E is the energy of the absorbed photons: E = hf
ϕ is the work function of the surface: ϕ = hf₀
= E - ϕ
Frequency f = 8.12×10¹⁸ Hz
Maximum kinetic energy = 4.16×10⁻¹⁷ J
Speed of light c = 3 x 10⁸ m/s
Planck's constant h = 6.63 × 10⁻³⁴ Js
E = hf = 6.63 × 10⁻³⁴ x 8.12×10¹⁸
E = 53.8356 x 10⁻¹⁶ J
from = E - ϕ ;
ϕ = E -
ϕ = 53.8356 x 10⁻¹⁶ - 4.16×10⁻¹⁷
ϕ = 53.4196 x 10⁻¹⁶ J
The work function of the metal ϕ = 53.4196 x 10⁻¹⁶ J
Answer:
The mass of air in the box is 0.78 grams.
Explanation:
A litre equals a cubic decimetre. By definition of density (), in grams per litre, we calculate the mass of air inside the cube (), in grams:
(1)
Where is the volume occupied by air within the cube, in litres.
If we know that and , then the mass of air is:
The mass of air in the box is 0.78 grams.