### All High School Physics Resources

## Example Questions

### Example Question #1 : Electricity

What is the maximum power consumption of portable CD player that draw a maximum of of current?

**Possible Answers:**

**Correct answer:**

The power in a circuit is equal to the current times the voltage.

### Example Question #1 : Electricity

The total amount of charge that passes through a wire’s full cross section at any point per unit of time is referred to as

**Possible Answers:**

Wattage

Electric potential

Current

Voltage

**Correct answer:**

Current

Current is defined as the amount of charge that passes through a specific area of a wire in a specific interval of time. It is measured in Amps which are Coulombs per second.

### Example Question #4 : Electricity

If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit

**Possible Answers:**

Decrease to one fourth its original value

Decrease to one half its original value

Increase by a factor of four

Increase by a factor of two

**Correct answer:**

Decrease to one half its original value

Decrease to one half its original value

The equation for Power is

According to Ohm’s Law

We can rearrange this equation for current as this is what is changing in our circuit.

We can then substitute this back into the power equation.

If we have the original value

and our second value

We can rearrange both for the voltage and set them equal to each other

,

So we can substitute this value in

And solve for

Therefore the power would be cut in half.

### Example Question #5 : Electricity

A current of flow in a wire. How many electrons are flowing past any point in the wire per second?

**Possible Answers:**

**Correct answer:**

The current is a measure of the amount of charge that passes a given point in a certain amount of time.

To determine how many electrons are passing this point we need to look at the charge of 1 electron and do a conversion.

### Example Question #1 : Electricity

The direction of conventional current is taken to be the direction that __________________ .

**Possible Answers:**

negative charges would flow

positive charges would flow

**Correct answer:**

positive charges would flow

We often think of current flowing from the top of the battery to the bottom of the battery. The top of the battery has a higher electrical potential than the bottom of the battery and is associated as being positive. Charges interact in such a way where like charges repel and opposite charges attract. Since we think of the charges traveling away from the positive end of the battery and toward the negative end of the battery, this would model the motion of a positive charge (away from positive and toward negative). Since it is not protons that move through the circuit, but rather electrons. It is more accurate to describe the flow of electrons from the negative side of the battery to the positive side.

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