Current Density and Resistance Concepts

This video tutorial covers calculations related to the electric field inside a conductor, potential difference, and resistance. It begins with an introduction to these concepts and proceeds to solve problems involving a cylindrical copper rod. The tutorial explains how to calculate current density, electric field, potential difference, and resistance, including how these values change with the length of the conductor. The video also explores the relationship between voltage, current, and resistance, and provides a detailed walkthrough of the calculations involved.

What is the formula for calculating current density in a conductor?

• Resistance divided by length

• Current divided by resistivity

• Current divided by cross-sectional area

• Voltage divided by resistance

How is the electric field inside a conductor calculated?

• By dividing voltage by current

• By multiplying resistivity by current density

• By dividing current by resistivity

• By multiplying voltage by resistance

What is the unit of the electric field inside a conductor?

• Ohms

• Amps

• Volts per meter

• Volts

How can the potential difference across a rod be determined?

• By multiplying electric field by the length of the rod

• By dividing current by resistance

• By multiplying current by resistivity

• By dividing voltage by length

What happens to the resistance of a rod if its length is quadrupled?

• It remains the same

• It halves

• It doubles

• It quadruples

What is the relationship between resistance and length of a rod if all other factors remain constant?

• Resistance is inversely proportional to length

• Resistance is proportional to the square of the length

• Resistance is directly proportional to length

• Resistance is independent of length

In the new problem, what is the electric field in a 100-meter copper rod with a 2-volt potential difference?

• 0.2 volts per meter

• 0.02 volts per meter

• 20 volts per meter

• 2 volts per meter

What is the resistance of a 100-meter copper rod with a 2-volt potential difference and a 4-amp current?

• 8 ohms

• 4 ohms

• 2 ohms

• 0.5 ohms

How is the current density in a rod calculated from the electric field and resistivity?

• Resistivity divided by electric field

• Electric field multiplied by resistivity

• Current divided by resistivity

• Electric field divided by resistivity

What is the cross-sectional area of a rod if the current is 4 amps and the current density is 1.163 x 10^6 A/m²?

• 0.044 x 10^-6 m²

• 44 x 10^-6 m²

• 4.4 x 10^-6 m²

• 0.44 x 10^-6 m²