Question 1

When an electric current exists within a conducting wire, which of the following statements describes the condition of any accompanying electric field?
A) must be perpendicular to current flow
B) must be parallel to current flow
C) must be zero
D) must be anti-parallel (opposite direction) to current flow

Accepted Answer

The electric field within a conductor is parallel to the current flow, as it is the electric field that drives the movement of charges (current) through the conductor.

Question 2

You measure a 20.0-V potential difference across a 5.00-$\Omega$ resistor. What is the current flowing through it?
A) 5.00 A
B) 4.00 A
C) 100 A
D) 1.00 A

Accepted Answer

B

Question 3

Two wires with the same resistance have the same diameter but different lengths. If wire 1 has length L₁ and wire 2 has length L₂, how do L₁ and L₂ compare if wire 1 is made from copper and wire 2 is made from aluminum? The resistivity of copper is 1.7 *10^-5 $\Omega$·m and the resistivity of aluminum is 2.82 *10^-5 $\Omega$·m. A) L₁ = 0.36 L₂ B) L₁ = 2.8 L₂ C) L₁ = 0.60 L₂ D) L₁ = 1.7 L₂

Accepted Answer

D

Question 4

The current in an electron beam in a cathode-ray tube is measured to be 280 µA. How many electrons hit the screen in 50 s? (e = 1.6 *10 ^- ¹⁹ C) A) 2.2 * 10¹¹electrons B) 8.8 * 10¹⁶ electrons C) 8.8* 10¹⁵ electrons D) 2.2 * 10¹⁵ electrons

Accepted Answer

The number of electrons can be calculated using the formula: Number of electrons = (Current × Time) / Charge of one electron. Substituting the given values: (280 × 10^-6 A × 50 s) / (1.6 × 10^-19 C) = 8.8 × 10^16 electrons.

Question 5

A 12.6-V battery supplies a 2.0-A current for 2.0 minutes. What is the work done by the battery during this process? A) 0 J B) 3.0 * 10³ J C) 2.5 *10² J D) 1.5 *10⁴ J

Accepted Answer

The work done by the battery is calculated using the formula: Work = Voltage × Current × Time. Here, Work = 12.6 V × 2.0 A × 120 s = 3024 J, which is approximately 3.0 × 10³ J.

Question 6

Wire A and Wire B are each carrying the same current. If the diameter of Wire A is half that of Wire B, how does the drift velocity v_dA in Wire A compare to that in Wire B? A) v_dA = 4 v_dB B) v_dA = 2 v_dB C) v_dA = v_dB /2 D) v_dA = v_dB /4

Accepted Answer

The answer of Wire A and Wire B are each...

Question 7

In a certain material there is a current of 16 A flowing through a surface to the left, and there is an equal amount of positive and negative charge passing through the surface producing the current. How much negative charge passes through the surface?
A) 16 C/s toward the left
B) 16 C/s toward the right
C) 8 C/s toward the right
D) 8 C/s toward the left

Accepted Answer

Since the current is 16 A and there is an equal amount of positive and negative charge, each type of charge contributes half to the total current. Therefore, 8 C/s of negative charge passes through the surface toward the right.

Question 8

The size of the electric current in a electrical conductor is a function of which of the following?
A) conductor cross sectional area
B) velocity of charge carriers
C) density of charge carriers
D) All of these choices are valid.

Accepted Answer

The electric current in a conductor depends on the cross-sectional area, the velocity of charge carriers, and the density of charge carriers, as all these factors influence the flow of charge.

Question 9

Two cylindrical resistors are made of the same material and have the same resistance. The resistors, R₁ and R₂, have different radii, r₁ and r₂, and different lengths, L₁ and L₂. Which of the following relative values for radii and lengths would result in equal resistances? A) r₁=r₂ and 4L₁= L₂ B) r₁=r₂ and L₁= 2L₂ C) 2r₁=r₂ and 4L₁= L₂ D) 2r₁=r₂ and L₁= 2L₂

Accepted Answer

The answer of Two cylindrical resistors are made of the...

Question 10

If a metallic wire of cross-sectional area 3.0 *10 ^- ⁶ m² carries a current of 9.1 A and has a mobile charge density of 4.24 * 10²⁸ carriers/m³, what is the average drift velocity of the mobile charge carriers? (charge value = 1.6 *10 ^- ¹⁹ C) A) 3.4 * 10³ m/s B) 1.7 * 10³ m/s C) 4.5*10 ^- ⁴ m/s D) 1.5 *10 ^- ⁴ m/s

Accepted Answer

The average drift velocity (v_d) can be calculated using the formula: v_d = I / (n * A * e), where I is the current, n is the charge density, A is the cross-sectional area, and e is the charge of an electron. Substituting the given values: v_d = 9.1 / (4.24 x 10^28 * 3.0 x 10^-6 * 1.6 x 10^-19) = 4.5 x 10^-4 m/s.

Question 11

How long is a wire made from 200 cm³ of copper if its resistance is 8.5 ohms? The resistivity of copper is 1.7 *10^-5 $\Omega$·m. A) 10 m B) 2.2 *10² m C) 7.1 m D) 3.0 *10³ m

Accepted Answer

The answer of How long is a wire made from...

Question 12

When you flip a switch to turn on a light, the delay before the light turns on is determined by:
A) the speed of the electric field moving in the wire.
B) the drift speed of the electrons in the wire.
C) the number of electron collisions per second in the wire.
D) none of these, since the light comes on instantly.

Accepted Answer

The delay is determined by the speed of the electric field, which propagates at nearly the speed of light, causing the light to turn on almost instantly.

Question 13

A lightbulb drawing a current of 0.60 A is run for 2.0 hours. How many electrons pass through the bulb during this process?
A) 
B) 
C) 
D)

Accepted Answer

The answer of A lightbulb drawing a current of 0.60...

Question 14

A metallic conductor has a resistivity of 18 *10 ^- ⁶ $\Omega$m. What is the resistance of a piece that is 15 m long and has a uniform cross sectional area of 6.0 *10 ^- ⁶ m²? A) 0.056 $\Omega$ B) 45 $\Omega$ C) 90 $\Omega$ D) 160 $\Omega$

Accepted Answer

The resistance R of a conductor is given by the formula R = ρL/A, where ρ is the resistivity, L is the length, and A is the cross-sectional area. Substituting the given values: R = (18 x 10^-6 Ω·m)(15 m) / (6.0 x 10^-6 m^2) = 45 Ω.

Question 15

A Nichrome wire has a radius of 0.50 mm and a resistivity of 1.5 *10 ^- ⁶ $\Omega$m. If the wire carries a current of 1.0 A, what is the potential difference per unit length along this wire? A) 1.9 V/m B) 0.95 V/m C) 1.6 V/m D) 0.003 V/m

Accepted Answer

The potential difference per unit length is given by:V/L = (ρI)/Awhere:ρ is the resistivity of the wireI is the current flowing through the wireA is the cross-sectional area of the wireSubstituting the given values into the equation, we get:V/L = [(1.5 × 10^-6 Ω·m)(1.0 A)]/π(0.50 × 10^-3 m)^2V/L = 1.9 V/mTherefore, the potential difference per unit length along the wire is 1.9 V/m.

Question 16

The unit of electric current, the ampere, is equivalent to which of the following?
A)" V/$\Omega$"
B) "V/s"
C) "$\Omega$.m"
D) "V.$\Omega$"

Accepted Answer

The answer of The unit of electric current, the ampere,...

Question 17

A 300-A·h battery can deliver how many coulombs starting from a full charge? A) 4.8 * 10³ B) 4.3 * 10⁴ C) 7.2 * 10⁵ D) 1.1 * 10⁶

Accepted Answer

The answer of A 300-A·h battery can deliver how many...

Question 18

A 0.10-m long metal rod has a radius of 1.0 cm and a resistance of 3.2 * 10 ^- ⁵ $\Omega$. What is the resistivity of the metal? A) 5.0 *10 ^- ⁸ $\Omega$.m B) 160*10 ^- ⁸ $\Omega$.m C) 10 *10 ^- ⁸ $\Omega$.m D) 1.6 *10 ^- ⁸$\Omega$.m

Accepted Answer

The answer of A 0.10-m long metal rod has a...

Question 19

If the current in a wire is halved, what effect does this have on the electron drift velocity in the wire?
A) It decreases by a factor of two.
B) It increases by a factor of four.
C) It stays the same.
D) It doubles.

Accepted Answer

According to Ohm's law, the electron drift velocity is proportional to the current. Therefore, if the current is halved, the electron drift velocity will also be halved.

Question 20

A wire carries a steady current of 0.1 A over a period of 200 s. What total charge passes through the wire in this time interval?
A) 2 C
B) 200 C
C) 0.005 C
D) 20 C

Accepted Answer

The answer of A wire carries a steady current of...

Quiz 19: Electric Currents and Circuits

When an electric current exists within a conducting wire, which of the following statements describes the condition of any accompanying electric field?

You measure a 20.0-V potential difference across a 5.00- $\Omega$ resistor. What is the current flowing through it?

The current in an electron beam in a cathode-ray tube is measured to be 280 µA. How many electrons hit the screen in 50 s? (e = 1.6 *10 ^- ¹⁹ C)

A 12.6-V battery supplies a 2.0-A current for 2.0 minutes. What is the work done by the battery during this process?

Wire A and Wire B are each carrying the same current. If the diameter of Wire A is half that of Wire B, how does the drift velocity v_dA in Wire A compare to that in Wire B?

In a certain material there is a current of 16 A flowing through a surface to the left, and there is an equal amount of positive and negative charge passing through the surface producing the current. How much negative charge passes through the surface?

The size of the electric current in a electrical conductor is a function of which of the following?

Two cylindrical resistors are made of the same material and have the same resistance. The resistors, R₁ and R₂, have different radii, r₁ and r₂, and different lengths, L₁ and L₂. Which of the following relative values for radii and lengths would result in equal resistances?

If a metallic wire of cross-sectional area 3.0 10 ^- ⁶ m² carries a current of 9.1 A and has a mobile charge density of 4.24 10²⁸ carriers/m³, what is the average drift velocity of the mobile charge carriers? (charge value = 1.6 *10 ^- ¹⁹ C)

How long is a wire made from 200 cm³ of copper if its resistance is 8.5 ohms? The resistivity of copper is 1.7 *10^-5 $\Omega$ ·m.

When you flip a switch to turn on a light, the delay before the light turns on is determined by:

A lightbulb drawing a current of 0.60 A is run for 2.0 hours. How many electrons pass through the bulb during this process?

A metallic conductor has a resistivity of 18 10 ^- ⁶ $\Omega$ m. What is the resistance of a piece that is 15 m long and has a uniform cross sectional area of 6.0 10 ^- ⁶ m²?

A Nichrome wire has a radius of 0.50 mm and a resistivity of 1.5 *10 ^- ⁶ $\Omega$ m. If the wire carries a current of 1.0 A, what is the potential difference per unit length along this wire?

The unit of electric current, the ampere, is equivalent to which of the following?

A 300-A·h battery can deliver how many coulombs starting from a full charge?

A 0.10-m long metal rod has a radius of 1.0 cm and a resistance of 3.2 * 10 ^- ⁵ $\Omega$ . What is the resistivity of the metal?

If the current in a wire is halved, what effect does this have on the electron drift velocity in the wire?

A wire carries a steady current of 0.1 A over a period of 200 s. What total charge passes through the wire in this time interval?

Quiz 19: Electric Currents and Circuits

When an electric current exists within a conducting wire, which of the following statements describes the condition of any accompanying electric field?

You measure a 20.0-V potential difference across a 5.00- Ω\OmegaΩ resistor. What is the current flowing through it?

The current in an electron beam in a cathode-ray tube is measured to be 280 µA. How many electrons hit the screen in 50 s? (e = 1.6 *10 - 19 C)