Which electromagnetic wave has the lowest frequencies (less than 3×109 hertz)?
2 answers:
Answer:
Radio waves
Explanation:
The electromagnetic spectrum includes all different types of waves, which are usually classified depending on their frequency. Ordering them from the highest frequency to the lowest frequency, they are:
- Gamma rays
- X-rays
- Ultraviolet
- Visible light
- Infrared radiation
- Microwaves
- Radio waves
Radio waves are the electromagnetic waves with lowest frequency, their frequency is lower than 300 GHz () and therefore they are the electromagnetic waves with lowest energy (in fact, the energy of an electromagnetic wave is proportional to its frequency). They are generally used for radio and telecommunications since this type of waves can travel up to long distances.
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Answer:
Refractive index of liquid C > Refractive index of liquid B > Refractive index of liquid A
Explanation:
Let the depth of each section is h.
That means the real depth for each section is h.
Apparent depth is liquid A is 7 cm.
Apparent depth in liquid B is 6 cm.
Apparent depth in liquid C is 5 cm.
by the formula of the refractive index
n = real depth / apparent depth
where, n is the refractive index of the liquid.
For liquid A:
.... (1)
For liquid B:
..... (2)
For liquid C:
..... (3)
By comparing all the three equations
nc > nB > nA
Refractive index of liquid C > Refractive index of liquid B > Refractive index of liquid A
Complete question is;
You push downward on a trunk at an angle 25° below the horizontal with a force of 750N. if the trunk is on a flat surface and the coefficient of static friction between the surface and the trunk is 0.61, what is the most massive trunk you will be able to move?
Answer:
The most massive trunk is about 81.3 kg
Explanation:
I've attached a free body diagram that depicts this question.
Where;
N = normal force on the trunk
m = mass of the trunk
W = weight of the trunk = mg
F = static frictional force
Using equilibrium of force in vertical direction, we obtain;
N = W + 750 Sin25
N = mg + 750 Sin25 - - - - (eq 1)
Now, we are given that Coefficient of static friction: μ = 0.61
static frictional force is given by the formula;
F = μN
Since N = mg + 750 Sin25, we now have;
F = (0.61) (mg + 750 Sin25) - - - (eq 2)
Along the horizontal direction, for the trunk to move, force equation must be;
F = 750 Cos25
Thus, we now have;
750 Cos25 = 0.61(mg + 750 Sin25)
g = 9.81.
So,we now have ;
750 Cos25 = 0.61(m(9.81) + 750Sin25)
750 × 0.9063 = 0.61(9.81m + (750 × 0.4226))
Divide both sides by 0.61;
(750 × 0.9063)/0.61 = 9.81m + 316.95
1114.3 = 9.81m + 316.95
1114.3 - 316.95 = 9.81m
797.35 = 9.81m
m = 797.35/9.81
m = 81.3 kg
F = normal force by each board on each side
W = weight of the board in between acting in down direction = 95.5 N
f = frictional force in upward direction by each board
= coefficient of friction = 0.663
Using equilibrium of force in Upward direction
f + f = W
f = W/2
f = 95.5/2 = 47.75 N
frictional force is given as
f = F
47.75 = (0.663) F
F = 72.02 N
