In other medium except vacuum, there is different speed in different EM wave, right?
i.e. speed of radio wave is faster than speed of gamma wave, right?
Vs/Vp = Ns/Np
This apply in transformer.
But I have read the following statement :
' Uasally , voltage ratio is larger than the turns ratio. This is because not all field lines from primary coil cut the secondary coil.'
Why? Is that mean some field lines 'go' to surroundings? :rolleyes:
1. potential difference = voltage?
2. What's the difference between electrical energy and electrical potential energy ?
3. In light bulbs, when the resistance is increased, is it brighter?
4. When voltmeter or ammeter is equipped with the electric circuit, will the light bulb in the circuit...
u have explained that visible light can be reflected by non-metal substances.
How about others(i.e. radio wave, microwave, infra-red, ultraviolet, X-ray, gamma ray)? Can they be reflected by non-metal substances?
4. Whether a substance is more likely to lose or to gain electrons depends on its particular properties
Do u have any examples of those properties?
I have 2 more question.
1. Why do we use sound wave as SONAR, not radio wave? If we use radio wave, what will happen?
2. Why don't we put...
~5 qestions~
1. EM wave can be reflected by metal surface only. Right?
2. SONAR can be reflected by any materials. Right?
3. Diffraction only occur when parallel wavefront(not circular wavefront) passes through the gap. Right?
4. After we use cloth to rub some substances, some are positive...
When we are playing bungy jump, we are instantaneous at rest at the bottom(K.E=0).
At that time, is elastic P.E. greater than gravitational P.E? :confused:
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Suppose that there is a net force from left hand side pushing the 'A' box to right hand side. During the pushing, 'B' box moves in right same as 'A'. According to my textbook, there is zero work done on 'B' because the force(weight) on the 'B' is at...
Suggest that one metal ball is removed in Newton's cradle. Like the following(thw second one is removed) :
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O OOO
Neglect the air resistance~
When we pull one ball(the left hand side one) of it to one side and then...
1. If a light ray go through a boundary of air and glass(i.e. angle of incidence is 90 degree), Is there any refraction or reflection?
2. If angle of incidence is 0 degree( the light ray is normal to a glass), Is there any reflection?
3. Suppose the situation is same as (2), but the light ray...
A boy travels by bus. When it goes up a mountain, does the boy inside the bus gain in P.E.? Vice versa, does he loss in P.E. when the bus goes down? :confused:
When we lift a heavy box to a higher position, energy from our bodies(chemical energy) is lost and there is energy gain(potential energy) in the box.
After, when we release the box from that position to the original one(lower position), there is P.E. lost in the box. So where does lost energy...
Suppose a boy is playing bumgy jump. When he jumps out and reachs the lowest bottom (instanteous at rest), there is zero K.E.
At that time, there is max. elelastic potential energy in the string. Which energy is changed to it(max. elelastic potential energy) :confused: ?
1. Suppose that a boy is pulling(Force: P) a train of 4 toy cars(The boy and toy cars are linked with a string) at a constant velocity.
The mass of each car is m kg. If friction is negligible, what is the tension of the string?
Is it equal to force P? That's my guess...