Current and Voltage

What is the difference between current and voltage?

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Electric Current•Is the measure of the number of electrical charges passing through a cross-section of a conductor in a given timee-

Electric Current

A French physicist who made important contributions to the theory of electricity and magnetism

•the symbol is capital letter I•the unit is A (ampere)

• Ampere (A) is named after Andre-Marie Ampere

Electric Current

•Is use to measure electric current in a circuit.

A Multi-meter

How to Use Multi-meter in testing current?•The positive terminal of the multi-meter is connected to the positive terminal of the circuit and the negative terminal of the multi-meter is connected to the negative terminal of the circuit.

Voltage•It is the energy that makes the charges move in a closed circuit

Voltage

He invented the voltaic pile, the forerunner of what we now call dry cell

•the symbol is capital letter V

•the unit is V (volt)• Volt (V) is named after Alessandro Volta

How to Use multi-meter in testing Voltage?

•The voltmeter is connected across a load in a circuit.

•If voltage is needed for charges to flow, how does the amount of voltage affect current?…let’s find out in the activity…

Current and

Voltage

Objectives:1.To measure the electric

current and voltage in a circuit using an ammeter and voltmeter respectively

2.To determine the relationship between electric current and voltage

Materials:• 1 ammeter• 2 dry cells (1.5V)• 4 connecting wires• 1 bulb• 1 bulb holder• 1 switch

Procedure #1:1. Construct a simple circuit

using a dry cell, a bulb, a switch and a multi-meter. Close the circuit by turning on the switch. Observe the bulb and the multi-meter. Record the multi-meter reading in table 1. Upon completion the task, switch off the circuit.

Procedure #1:

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Ammeter connected in a circuit

Ammeter connected in a circuit with one dry cell

Q1. What is the reading on the ammeter?

Procedure #2:Add another dry cell to the circuit. Record the electric current measurement in Table 1. Once the task is done, turn off the switch.

Procedure #2:

Ammeter connected in a circuit with two dry cells

Q2. Compare the brightness of the bulb with one dry cell to its brightness when there are two dry cells in the circuit.

Q3. What is the ammeter reading this time?

Q4. What can be inferred about the current passing through the bulb?

Procedure #3:Connect the voltmeter as shown in figure 5. Switch on and record the voltage in Table 1. Once the task is done, turn off the switch.

Voltmeter connected in a circuit with one dry cell

Q5. What is the voltmeter reading?

Procedure #4:Add another dry cell to the circuit. Record the voltmeter reading in Table 1. Observe the brightness of the bulb. Once the task is done, turn off the switch.

Voltmeter connected in a circuit with two dry cells

Q5. What is the voltmeter reading?

Q6. Describe the brightness of the bulb.

Q7. What is the voltmeter reading this time?

Q8. What can you inferred about the voltage across the bulb?

Q9. Refer to the table 1, how are voltage and current related?

Thank you for listenin

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Thank you for listenin

g!

Thank you for listenin

g!