Cracking the SAT Physics Subject Test

Chapter 10 Electric Potential and Capacitance When an object moves in a gravitational field, it usually experiences a change in ...

ELECTRICAL POTENTIAL ENERGY As we said, when a charge moves in an electric field, unless its displacement is always perpendicula ...

What is its change in electrical potential energy? Here’s How to Crack It Since the field is uniform, the electric force that th ...

Here’s How to Crack It In this case, an outside agent must be pushing the charge to make it move because the electric force natu ...

ELECTRIC POTENTIAL Consider a point charge q 1 at a distance r 1 from a fixed charge q 2 moving by some means to a position r 2. ...

The change in electric potential, ∆V, is defined as this ratio. It’s Potentially Important The potential of a single point in sp ...

Let Q = 2 × 10−9 C. What is the potential at a point P that is 2 cm from Q? Here’s How to Crack It Relative to V = 0 at infini ...

How much work is done by the electric field as a charge moves along an equipotential surface? Here’s How to Crack It If the ch ...

Two large, flat plates—one carrying a charge of +Q, the other −Q—are separated by a distance d. The electric field between the ...

This tells us that the potential of the positive plate is greater than the potential of the negative plate, by the amount Ed. Th ...

The Principle of Superposition for Electric Potential The formula Φ = kQ/r tells us how to find the potential due to a single po ...

potential at A due to Q 2 alone (ignoring the presence of Q 1 ) is ΦA2 = k Q 2 /rA2 = (9 × 10^9 )(−5 × 10−9)/(5 × 10−2) = −900 V ...

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CAPACITANCE You may see a question on capacitors on the SAT Physics Subject Test, so let’s discuss them now. Consider two conduc ...

so the greater the voltage applied to the capacitor, the greater the amount of charge that can be held by the capacitor. Capacit ...

From the equation C = , we can calculate the area, A, of each plate. ...

ELECTRIC FIELD AND CAPACITORS When we studied electric fields in the preceding chapter, we noticed that the electric field creat ...

mm. The device’s capacitance is 1μF. How much charge needs to be transferred from one plate to the other in order to create a un ...

Solving for t, ...

DIELECTRICS One method of keeping the plates of a capacitor apart, which is necessary to maintain charge separation and store po ...