Lightbulboutput-TwoThirtyVolts.docVIP

Lesson Plan: Electric Current (age 11 – 14) – The light output from a light bulb. Objectives: By the end of the session students will understand the relationship between the output of light from a light bulb and the electrical power used by a light bulb. Lesson introduction (15 min): Recap on previous learning on electric current. Explain experiment and learning objectives. Lesson activity (25 min): Group students in pairs and task them to set up the two circuits shown in the diagram, one for the light bulb and one for the LDR. The current through the LDR will alter as the amount of light falling on it from the light bulb alters. Students to switch on the power supply and adjust the output until it is about 24W. This might be a voltage of 12V and a current of 2 A. The LDR is then moved towards the bulb until the milliammeter reads the biggest current that it can (do not let it touch the bulb). Students to record the current in the bulb, the voltage across it and the current in the milliammeter. The power supply to then be altered so that the bulb is a little dimmer, and another set of readings taken. This is to be repeated for two more power supply settings. The students are to record the results in a table. Lesson demonstration (15 min): Select some of the students to inform the rest of the class about their findings. The remainder of the answers to the questions posed could be displayed for others to see and read. Demonstration experiment on Electric Current at can be used to re-enforce learning. Lesson review (5 min): Recap on learning from experiment and establish levels of understanding. Student Quiz on Electric Current at can be used by students to test understand. Resources required: A 12V 24W bulb, a variable voltage 12V dc power supply, leads, a light dependent resistor (LDR) such as an ORP12, milliammeter, voltmeter, ammeter and a battery pack (12 V). Expected Outcomes: Students will understand the relationship between the ou