CPD Workshops

BrightSparks Circuits

by Amy Collins August 10, 2018

This activity was created as part of a Gratnells What’s In My Tray CPD workshop for secondary science technicians to support practical work and delivery of the curriculum. It can be carried out as a stand-alone activity for students or combined with other activities from the session to form a STEM carousel.

BrightSparks – develop your circuitry skills

The modules, leads, multimeter and hand crank are all available from BrightSparks 4kids who are the creator of this What’s In My Tray Activity.

You will need (per team of 4):

  • Shallow Gratnells (F1) tray with a four section insert to organise the modules and lid
  • 2 x Bulb module
  • 1 x Diode module
  • 1 x Two Way Switch module
  • 2 x Capacitor module
  • Digital Multimeter with operating manual
  • 8 x Connecting leads
  • 1 x Hand crank
  • 2 x Stopwatch

This activity also works as an individual challenge, just increase the amount of time allocated to complete it.


  • Place all the equipment into the shallow Gratnells (F1) tray as per the picture below and put the lid on.

What to do:

  • Use the equipment in the tray to construct the following circuit

  • Set the Two Way Switch module to ‘Charge’ mode
  • Rotate the hand crank clockwise at medium speed (~2 revolutions per second) for 30 seconds – you should observe a steady 5 to 6 Volts on the Multimeter.
  • Flip the Two Way Switch module to ‘Run’ mode, immediately start the stopwatch and note down the Voltage displayed on the Multimeter.
  • Time how long the Bulb module will operate from a single charged capacitor until exhausted – exhaustion is a reading of 1.0 Volt on the Multimeter.
  • Take a reading from the Multimeter every 10 seconds.
  • Plot your results on the graph provided and add a line of best fit.

Answer the following questions:

  • How long did the Bulb operate for from a single charged capacitor until exhausted at 1.0 Volt?
  • How long could we operate two equal power bulbs modules in parallel from a single charged capacitor?
  • Why did we only operate the hand crank in a clockwise direction?
  • Name one purpose of the Diode module in this circuit.
  • What is the capacitance value of the capacitor? Tip – Look closely, it is measured in Farads (F)
  • Estimate the total value of capacitance needed to operate one bulb module for 1 hour?


  • Around 30 seconds
  • Half the time of the answer given to Q1, so around 15 seconds
  • So the polarity output would be the correct way for our circuit
  • Prevents current from flowing in the opposite direction once the capacitor is charged, therefore maintaining its charge if we stopped rotating.
  • OR A safety component for the capacitor to protect it from reverse polarity if the hand crack is rotated in the wrong direction.
  • 1 Farad or 1F
  • Based on the answer given to Q1, if 1 Farad capacitance provides 30 seconds bulb operation, we would need 120 Farads for 1 hour of operation.

For more images and videos of this activity taken at the National Technicians Conference in York see here. 

Health & Safety

As with all Gratnells Learning Rooms What’s In My Tray Activities, you should carry out your own risk assessment prior to undertaking any of the activities or demonstrations.