# Electric Fields

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How do protons travel in electric fields?
Protons in a uniform electric field travel from the positive to negative terminal. They lose Ep energy.
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What are formulae for force and electric field strength in a uniform field?
Felectric=Eq and E=V/d
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What's the formula for charges travelling through an electric field?
The formula for charges travelling through an electric field with equipotentials is E=-dV/dr
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How is Milikan's Oil Drop experiment carried out?
Squirt oil in a metal hole. A weak radioactive source ionises it. Make electric field and gravitational field equal then allow drop to fall to terminal velocity. Time fall and use viscosity to calculate drop's radius and then mass. Use q=mgd/V
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What does the inverse square law state?
The inverse square law says when the diameter doubles, area is multiplied by four and luminous intensity is 4x less.
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What links E, Q, and r^2 in proportion?
Spacing of field lines indicates strength. Density of field lines = N/4 * pi * r^2. E is proportional to Q/r^2
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What are the formulae for E, V, F, and Ep?
E=kQ/r^2 V=kQ/r F=kqQ/r^2, and Ep=kqQ/r
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What variables are vectors and what variables are scalars?
Electric field and force are vectors, and electric potential and Ep are scalars.
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How do electrons travel in uniform fields when accelerated from a cathode?
An electron is released from a hot cathode and accelerated to 1/2mv^2, losing Ep. It then travels across deflection plates with constant horizontal velocity.
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What's force in a wire when magnetic field is applied?
Ftotal = ILB=qvB Force on one electron = Ftotal/N
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What is the centripetal force formula?
Centripetal force is mv^2/r which is equal to Bqv. A B-field path is circular.
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## Other cards in this set

### Card 2

#### Front

What are formulae for force and electric field strength in a uniform field?

#### Back

Felectric=Eq and E=V/d

### Card 3

#### Front

What's the formula for charges travelling through an electric field?

#### Back ### Card 4

#### Front

How is Milikan's Oil Drop experiment carried out?

#### Back ### Card 5

#### Front

What does the inverse square law state?

#### Back 