Electric Current and Ohm's Law Quiz

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Questions and Answers

What is the unit of electric current?

Ampere (correct)
Watt
Volt
Ohm

According to Ohm's Law, current is directly proportional to which of the following?

Mobility
Current Density
Resistance
Potential Difference (correct)

What does current density (J) measure?

Total current in a conductor
Voltage drop across a resistor
Average electron velocity
Current per unit cross-sectional area (correct)

What is the formula for drift velocity (Vd)?

Vd = I / neA (D) Signup and view all the answers

What does mobility (µ) represent?

Ease of electron movement through a material (C) Signup and view all the answers

What is the relationship between voltage (∆V), current (I), and resistance (R) as per Ohm's Law?

∆V / I = R (D) Signup and view all the answers

The formula for conductivity (σ) is derived from which concept?

Resistance (B) Signup and view all the answers

Which of the following represents the average velocity of electrons in a conductor?

Drift Velocity (D) Signup and view all the answers

In a Voltage vs Current graph according to Ohm's Law, what does the slope represent?

Resistance (A) Signup and view all the answers

What does resistivity (ρ) measure?

Resistance per unit length and area (C) Signup and view all the answers

What is the correct formula for terminal voltage in terms of emf and internal resistance?

V = ε - Ir (B) Signup and view all the answers

In a series combination of cells, how is the equivalent emf calculated?

εeq = ε1 + ε2 (C) Signup and view all the answers

What is the relationship for equivalent internal resistance in a series combination of cells?

req = r1 + r2 (C) Signup and view all the answers

What type of resistance is added in series with a galvanometer to convert it to a voltmeter?

High resistance (A) Signup and view all the answers

Which feature best describes an ideal voltmeter?

Has infinite internal resistance (B) Signup and view all the answers

How do you calculate power dissipated in a resistor?

P = I^2R (B) Signup and view all the answers

What happens to the equivalent emf in a parallel combination of cells with the same emf?

It remains the same (C) Signup and view all the answers

What is the purpose of a meter bridge?

To measure unknown resistances (D) Signup and view all the answers

In the formula R = (100 - l1) * S / l1, what does R represent?

Unknown resistance (A) Signup and view all the answers

What is the effect of internal resistance on terminal voltage?

It decreases the terminal voltage (A) Signup and view all the answers

What happens to the resistance of a semiconductor as temperature increases?

Resistance decreases (B) Signup and view all the answers

Which formula represents the total resistance in a series combination of two resistors?

$Req = R_1 + R_2$ (D) Signup and view all the answers

According to Kirchhoff's Current Law, how is current defined at a junction?

I_in is equal to I_out (D) Signup and view all the answers

What does the equation $E = V + IR$ express in relation to a cell?

The relationship between EMF, terminal voltage, and internal resistance (A) Signup and view all the answers

How do you calculate the equivalent resistance in a parallel circuit with two resistors?

$Req = rac{R_1R_2}{R_1 + R_2}$ (D) Signup and view all the answers

Which statement correctly describes the temperature coefficient of resistance for alloys like Nichrome?

They have a temperature coefficient of $x=0$ (B) Signup and view all the answers

What does the voltage drop equation, $ΔV = V_2 - V_1$, represent?

The decrease in voltage across a resistor (B) Signup and view all the answers

Which geometrical measure is represented by the formula for the body diagonal of a cube?

Distance across the cube from corner to opposite corner (A) Signup and view all the answers

What could happen to an insulator's resistance when subjected to a change in temperature?

Resistance may have a small, yet measurable change (B) Signup and view all the answers

What is the main purpose of a Wheatstone Bridge?

Finding unknown resistance (A) Signup and view all the answers

What is the potential gradient when potential difference is $V$ and length is $L$?

k = rac{V}{L} (D) Signup and view all the answers

What happens to the total emf when cells are connected in series?

It is the sum of individual emfs. (B) Signup and view all the answers

In a closed circuit, which equation represents the relationship between emf, current, and internal resistance?

E = I R + I r (B) Signup and view all the answers

What is the total emf when cells are connected in parallel?

The total emf is the same as the emf of a single cell. (C) Signup and view all the answers

How is internal resistance calculated using a potentiometer?

Using a combination of emf and resistance measurements. (C) Signup and view all the answers

What is the measure of current in the case of an open circuit?

I equals zero. (C) Signup and view all the answers

What is the formula for calculating the magnetic field strength around a long wire?

$B = rac{ u_0 I}{2 ext{pi} a}$ (C) Signup and view all the answers

When comparing the emf of two cells, what does a positive reading indicate?

The first cell has a larger emf. (D) Signup and view all the answers

When resistors are connected in parallel, how is the total current calculated?

$I = rac{ ext{E}}{R_1 + R_2}$ (B) Signup and view all the answers

What does the internal resistance of a battery affect in a closed circuit?

It reduces the effective voltage available to the load. (A) Signup and view all the answers

Flashcards

Electric Current

The rate of flow of electric charge.

Unit of Current

Ampere (A)

Potential Difference

The difference in electric potential between two points, measured in volts.

Ohm's Law

The current through a conductor between two points is directly proportional to the voltage across the two points.