Electricity and Current Calculations

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Questions and Answers

What is the relationship defined by Ohm's Law?

Resistance is directly proportional to voltage.

Voltage is independent of both current and resistance.

Current is directly proportional to voltage and inversely proportional to resistance. (correct)

Current is directly proportional to resistance.

If a light bulb has a resistance of 6 ohms and a current of 35 mA flows through it, what is the potential difference across the light bulb?

0.15 V

0.21 V (correct)

0.50 V

0.30 V

What would be the current flowing through a device with a resistance of 44 ohms connected to a potential difference of 220 V?

4 A (correct)

2 A

5 A

10 A

For a copper wire with a resistance of 25 ohms connected with a potential difference of 50 V, what is the current flow through it?

2 A Signup and view all the answers

A voltmeter reads 20 V across a resistance of 50 ohms. What is the current flowing through this resistance?

0.4 A Signup and view all the answers

What happens to the current flow in a circuit when resistance is increased?

Current flow decreases Signup and view all the answers

Which instrument is used to measure electric current?

Ammeter Signup and view all the answers

If a current of 0.8 A flows for 4 minutes, how is the total charge calculated?

Q = I × t Signup and view all the answers

What type of current always flows in one direction?

Direct Current (DC) Signup and view all the answers

How is potential difference measured between two points in a circuit?

By connecting a voltmeter in parallel Signup and view all the answers

What unit is used to measure electric resistance?

Ohm Signup and view all the answers

When 3x10⁵ coulombs pass through a wire in 2.5 seconds, what is the current flow?

150 A Signup and view all the answers

Which of the following statements is true regarding the properties of electric current?

Low resistance restricts current flow Signup and view all the answers

How does the cross-sectional area of a conduction wire affect its resistance?

A larger cross-sectional area decreases resistance. Signup and view all the answers

If the length of a conduction wire is doubled, what happens to its resistance?

Resistance doubles. Signup and view all the answers

In the formula $R = \frac{\rho l}{A}$, what does the symbol $\rho$ represent?

Resistivity of the material. Signup and view all the answers

When comparing two wires made of the same metal, how does a wire with a greater length affect its resistance?

It has higher resistance. Signup and view all the answers

If two metals have a resistivity ratio of 4:5 and equal lengths, how does their resistance compare?

Resistance ratio is 4:5. Signup and view all the answers

What is the effect on resistance when the diameter of a wire is increased while keeping other factors constant?

Resistance decreases. Signup and view all the answers

If the resistivity of metal A is 8x10^-8 Ωm and its length is 2m with a cross-sectional area of 0.05 cm², what is its resistance?

0.10 Ω. Signup and view all the answers

Which statement correctly describes the relationship between resistance and cross-sectional area when both length and resistivity are constant?

Resistance is inversely proportional to the cross-sectional area. Signup and view all the answers

Study Notes

Electricity and Electrical Energy

Electricity is a form of energy that can be transformed from other energy forms and vice versa.
Current is defined as the flow of electric charge through a conductor, typically measured at a specific point in time. It represents how much electric charge flows past a given point in the circuit over the period of one second, impacting the circuit's overall performance.Electric

Electric Current Calculation

- Current (I) = Charge (Q) / Time (t)
  - I is measured in Amperes (A), which indicates the flow rate of electric charge in a circuit. One ampere represents one coulomb of charge passing through a given point in one second.
  - Q is measured in Coulombs (C), the unit of electric charge, where one coulomb is defined as the amount of electric charge that is moved by a constant current of one ampere over a duration of one second. This relationship helps to quantify not only the total charge in motion but also provides insight into the fundamental particle behavior of electrons as they traverse through a conductive medium, ultimately influencing how electrical energy is transmitted and utilized within various components of an electrical system.
  - t is measured in seconds (s) and represents the duration over which the charge is flowing. This time factor is crucial for understanding how current behaves in electrical circuits.

Practice Problems

Problem 1: Calculate the current when a charge of 3 x 10-5 coulombs passes through a wire in 2.5 seconds.
Answer: 1.2 x 10-5 A
Problem 2: Find the charge that passes through a wire with a current of 25 mA for 5 minutes.
- Answer: 75 coulombs
Problem 3: A current of 0.8 A flows through a wire for 4 minutes. Determine the number of electrons passing through the wire.
- Answer: 1.92 x 1021 electrons
Problem 4: Calculate the charge flowing through a wire between 0 and 10 seconds based on the provided graph.
- Answer: 7.5 Coulombs

Ohm's Law

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance between them.
V = I x R (Voltage = Current x Resistance)
- V is measured in Volts (V)
- I is measured in Amperes (A)
- R is measured in Ohms (Ω)

Ohm's Law Practice Problems

Problem 1: A current of 35 mA flows through a light bulb with a resistance of 6 Ω. Calculate the potential difference across the bulb.
Answer: 0.21 V
Problem 2: An electric device with 44Ω resistance is connected with a 220V potential difference. Determine the current flowing through the device.
Answer: 5 A
Problem 3: A copper wire with 25Ω resistance is connected to a 50V potential difference. Calculate the current.
Answer: 2 A

Additional Notes

Types of Current: Direct Current (DC) flows in one direction, while Alternating Current (AC) flows in two directions.
Resistance: Resistance is the property of an object that opposes the flow of current in a circuit. It's measured in Ohms (Ω).
Potential Difference: The potential difference between two points is the energy lost by one coulomb of charge as it passes between the two points. It is measured in Volts (V)

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Description

Test your knowledge of electricity and electric current calculations with this quiz. You will solve problems involving charge, current, and the relationship between them, based on fundamental principles of electricity. Perfect for students learning about electricity in their physics classes.