Drift Velocity

In the equation I = nAvq, what does v represent?

• The average velocity of the electrons in random directions

• The highest velocity of the electrons in random directions

• The average velocity of the electrons in the direction of the electric field

• The highest velocity of the electrons in the direction of the electric field

In the equation I=nAvq, which option(s) describe the meaning of n?

• the number of charge carriers in the wires

• the number of charge carriers per unit volume

• the total charge carriers available in the battery

• the charge per unit volume

When a thick wire is connected in series with a thin wire of the same material which of the below is/are true?

• The current through the thick wire is greater than the current through the thin wire

• The electrons move slower through the thin wire than through the thick wire

• The number of charge carriers per unit volume is greater in the thick wire than in the thin wire

• The number of charges flowing per second past a cross section of the thick wire is the same as that flowing past a cross section of the thin wire

When a semiconducting and metallic wire of the same diameter are connected in series which of the below is/are true?

• The current in the semiconductor is greater than that in the metal

• The electrons move faster in the semiconductor

• The semiconductor has a higher value of n

• Each charge carrier in the semiconductor carries more charge than the charge carriers in the metal

If the current in a specific copper wire increases this can be due to _____________________.

• An increase in the charge carrier density

• An increase in the electron drift speed

• An increase in its cross sectional area

• An increase in the charge of electrons

If the current in a metal conductor were to remain the same, what effect will doubling the charge carrier density, n, have?

• Double the charge per charge carrier in the material

• Halve the average drift speed of the electrons

• Double the cross sectional area of the wire

• Halve the length of the conductor

The diagram at the right shows two identical resistors - R1 and R2 - placed in a circuit with a 12-Volt battery. If a third resistor (R3), identical to the other two, is added in parallel with the first two, then the overall resistance will ____ and the overall current will ____.

• increase, increase

• decrease, decrease

• increase, decrease

• decrease, increase

A high resistance light bulb and a low resistance light bulb are connected in series to a 6-Volt pack of batteries. Which of the two light bulbs will shine the brightest?

• They will have the same brightness.

• The low-R bulb will shine more brightly.

• The high-R bulb will shine more brightly.

• None of the above

If the current at a given point in a circuit is 2.5 Amp, then how many electrons pass that point on the circuit in a time period of 1 minute.

Answer:

• 9.375 x 10²⁰ electrons

• 9.375 x 10²¹ electrons

• 9.375 x 10¹⁹ electrons

• 9.375 x 10¹⁸ electrons

Calculate the drift velocity of electrons in a wire of diameter 0.0032 m that has 2.5 x 10²⁰ electrons per m³, and a current of 0.043 A.

Charge of electron = 1.60 x 10^-19 C