Answer:
2400 Hz
Explanation:
frequency = speed × lenght of the wave
In the first figure, the surface absorbs all colors except for green light, which is reflected: so, the surface will appear as green to our eyes, because green is the only color which is reflected by that surface.
Similarly, in the second figure, the surface absorbs all colors except for blue, and so the surface will appear blue to our eyes.
In the third figure, the surface absorbs all colors, so it will appear black to our eyes (because no colors are reflected, and black=absence of colors).
In the fourth figure, all colors are reflected: this means the surface will appear white to our eyes (white= sum of all colors).
Answer:
a) 6498.84 kW
b) 0.51
c) 0.379
Explanation:
See the attached picture below for the solution
Answer:
22.2 W
Explanation:
First of all, we calculate the work done by moving the wagon, using the formula:

where
F = 20 N is the magnitude of the force
d = 1000 m is the displacement of the wagon
is the angle between the direction of the force and of the displacement (assuming the force is applied in the direction of motion)
Substituting, we find

Now we can find the power generated, which is equal to the ratio between the work done and the time taken:

where
W = 20,000 J
t = 15 min = 900 s
Substituting,

And the same value in Joules/second (remember that 1 Watt = 1 Joule/second)
Answer:
(a) = -0.16%
(b) = smaller
Explanation:
given
power = 460 W
potential difference = 120 V
(a) what percentage will its heat output drop if the applied potential difference drops to 110 V ?
we know
.....................(i)
we need to find change in power
..............(ii)
from equations we get



(b)
if we increase temperature resistance will increase and decrease with decrease in temperature and we know power is inversely proportional to resistance so if potential decrease and it would cause drop in power
and due to this increment of heating power resistance will decrease so actual drop in the power would be smaller