## 12 Questions

What is the unit of electric current, and how is it defined?

The unit of electric current is the ampere (A), and it is defined as 1 coulomb per second (1 A = 1 C/s).

What is the direction of flow of conventional current and electron flow in a circuit?

Conventional current flows from the positive terminal to the negative terminal, whereas electron flow is from the negative terminal to the positive terminal.

What is the relationship between voltage, current, and resistance according to Ohm's Law?

The voltage (V) is equal to the product of current (I) and resistance (R), i.e., V = I × R.

How does the voltage and resistance affect the current in a circuit?

If the resistance is kept constant, increasing the voltage will increase the current, and increasing the resistance will decrease the current.

What is electric power, and how is it related to voltage and current?

Electric power (P) is the product of voltage (V) and current (I), i.e., P = V × I.

What is the relationship between electric power and resistance?

The electric power (P) can also be expressed as P = I^2 × R or P = V^2 / R, showing the relationship with resistance (R).

What is the relationship between the power delivered by a battery and the power dissipated by a resistor?

The power delivered by the battery is equal to the power dissipated by the resistor.

A motor uses 50 watts of power and draws a current of 400 milliamps. What is the voltage across the motor?

125 volts

What is the internal resistance of the motor calculated using Ohm's Law?

312.5 ohms

What is the electric current flowing through a 5 kilo-ohm resistor if 12.5 coulombs of electric charge flow through it in 8 minutes?

26 milliamps or 0.026 amps

What is the power consumed by the resistor if the electric current flowing through it is 26 milliamps and the resistance is 5 kilo-ohms?

3.38 watts

What is the voltage across the resistor if the electric current flowing through it is 26 milliamps and the resistance is 5 kilo-ohms?

approximately 130 volts

## Study Notes

- Conventional current is the flow of positive charge from the positive terminal to the negative terminal, whereas electron flow is from the negative terminal to the positive terminal.
- Current is defined as the rate of charge flow, or charge divided by time (Δq / Δt), and its unit is the amp (1 amp = 1 coulomb per second).
- Electric charge is associated with the quantity of charged particles, and an electron has a charge of 1.6 × 10^(-19) coulombs, which is negative.
- Ohm's Law describes the relationship between voltage, current, and resistance, where voltage is the product of current and resistance (V = I × R).
- If the resistance is kept constant, increasing the voltage will increase the current, and increasing the resistance will decrease the current.
- The voltage and current are directly related, while the resistance and current are inversely related.
- Electric power is the product of voltage and current, and it can be expressed in three forms: P = V × I, P = I^2 × R, and P = V^2 / R.
- Power is measured in watts, and 1 watt is equal to 1 joule per second.
- A current of 3.8 amps flowing for 12 minutes results in a charge of 2736 coulombs passing through any point in the circuit.
- The number of electrons represented by this charge is approximately 1.71 × 10^22 electrons.
- A 9-volt battery connected to a 250-ohm resistor results in a current of 0.036 amps, or 36 milliamps.
- The power dissipated by the resistor is 0.324 watts, or 324 milliwatts.
- The power delivered by the battery is equal to the power dissipated by the resistor, which is 0.324 watts.
- A 12-volt battery connected to a light bulb drawing 150 milliamps of current results in an electrical resistance of the light bulb of 80 ohms.
- The power consumed by the light bulb is 1.8 watts.
- The cost of operating the light bulb for a month, given a cost of electricity of 11 cents per kilowatt-hour, is approximately 14 cents.
- A motor using 50 watts of power and drawing a current of 400 milliamps has a voltage across it of 125 volts.- Voltage of the motor is 125 volts.
- Internal resistance of the motor is 312.5 ohms, calculated using Ohm's Law (v = iR) with voltage 125 volts and current 0.4 amps.
- Two important equations in solving common problems are P = VI and V = IR.
- Electric charge flowing through a 5 kilo-ohm resistor is 12.5 coulombs in 8 minutes.
- Electric current is the rate of charge flow, calculated by dividing the change in electric charge by the change in time.
- 8 minutes converted to seconds is 480 seconds.
- Electric current flowing through the resistor is 0.026 amps or 26 milliamps, calculated by dividing the charge (12.5 coulombs) by the time (480 seconds).
- Power consumed by the resistor is 3.38 watts, calculated using the equation P = I^2R with current 0.026 amps and resistance 5 kilo-ohms.
- Voltage across the resistor is approximately 130 volts, calculated using the equation V = IR with current 0.026 amps and resistance 5 kilo-ohms.

Test your understanding of electric circuits, Ohm's Law, and related concepts such as voltage, current, resistance, and power. Covers calculations of electric charge, current, and power consumption.

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