Ohm's Law and Resistance Review

Ohm's Law

Welcome!

Are you excited for a fun learning session?

Objective: At the end of the discussion, the students should be able to:

a) define current, voltage and resistance;
b) state Ohm’s Law;
c) utilize simulation tools to observe the relationship between voltage, current, and resistance.; and
d) give example of real-life application of Ohm's Law.

Decipher Me

Anagram words will be shown, and you need to decipher the anagram word.

Example:
•SILENT
•LISTEN

Reshuffle the letters in the given word to create another word.

CIRCUIT

Electric Circuit, path for transmitting electric current.

LAMP

This is a device for giving light.

WIRE

Use to connect components in a
circuit.

VOLTAGE

Voltage describes the “pressure” that pushes electricity. The amount of voltage is indicated by a unit known as volt (V).

CURRENT

It is the movement of charges

BATTERY

In an electric circuit, the role of a battery is to supply energy to the circuit.

CONDUCTORS

are substances that allow electricity to pass through them freely.

RESISTANCE

Resistance is a measure of the opposition to current flow in an electrical circuit

  Ω (ohm)

BATTERY

LAMP

WIRE

VOLTAGE

RESISTANCE

CURRENT

CIRCUIT

CONDUCTORS

BATTERY

LAMP

WIRE

SWITCH

It is a conducting loop in which current can transfer electrical energy from a suitable source to a useful load.

Electric Circuit

BATTERY

LAMP

WIRE

SWITCH

​Resistance

​Current

​Voltage

Voltage

Volt (V)

Resistance Current

Ohm (Ω)

Ampere (A)

OHM'S

LAWLAW

Ohm's Law

​

​German physicist named Georg Simon
Ohm discovered the relationship between the current, voltage and resistance.

It is stated that as, “current is directly proportional to the voltage and inversely proportional to the resistance”.

Ohm’s Law Activity

Procedure:

1. Familirize yourself with the Ohms Law simulation.
2. Move the resistance slider to about 100 Ω. You will keep the resistance at this value. Do not move the slider again for this part of the experiment.
3. Move the slider to 1 V.
4. Record the current in mA in the Data Table 1 below and convert it to Amperes (A)
5. Repeat the process in increments of 1 V making sure you record the current for each increment.

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Voltage (V)

Voltage (V)

Current (mA)

​Table 1

​Voltage (V)	​ Current (mA)	​Current (A)
​1	​	​
2​	​	​
3​	​	​
4​	​	​
5​	​	​
6​	​	​
7​	​	​
8​	​	​
9​	​	​

Analysis of data

• Plot your data. Plot current (A) on the Y axis and plot Voltage on the x-axis.

• The slope of your graph is 1/R. What type of relationship is given by the graph?_____________________

• What is the resistance?_______________________

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Generalization

Application

We can control the speed of the fans at our homes by moving
the regulator to and fro. Here the current flowing through the
fan is controlled by regulating the resistance through the
regulator. A circular knob on the component can be rotated to
achieve a variable resistance on the output terminals. For any
specific value of the input, we can calculate the resistance,
current and thus power flowing through Ohm’s Law.

Conventional Fans

Application

Mobile and Laptop chargers use DC power supply in the
operation. DC power supply provides a variable output voltage
based on the resistance and the overall working is controlled
by Ohm’s law.

Mobile or Laptop Charger

In the ½ sheet of paper, answer the following question. Show
your complete solution.

1. Does a battery produce current? How?
2. What voltage is needed to cause a 2A current flow through a 10Ω
resistor?
3. A circuit is wired with a power supply, a resistor and has a current of
30mA. Determine the new current if the voltage was increased by a
factor of 2 and the resistance was decreased by a factor of 3.