Electromagnetic Induction

taught by Math Arena

Course description


This course is targeted at Singapore Cambridge GCE O level students, but is also relevant to IGCSE students and Singapore's Integrated program students.

When you think of electricity, you might be imagining a current that flows from one point to another. That's direct current. The power in our houses, however, is very different. We use alternating current, which keeps on changing the direction it flows in. It turns out that there's a very good reason for doing so - distributing power to our houses would be much harder using direct current. But what does this have to do with electromagnetic induction? Join us and find out!

Course Content

You will learn:

  • Why putting two coils of wire next to each other and running a current through one of them will cause them to jump
  • How to generate electricity
  • How to tweak alternating voltages to the values you want
  • How to detect earthquakes using magnets
  • Lots of other cool stuff!

A link to the full O level Physics syllabus can be found here

Course Prerequisites

You will need to know:

  • How to watch videos on your computer
  • It is encouraged that you complete the courses on Magnetism and Electromagnetism first. Familiart
Math Arena
Math Arena

The instructor is from Math Arena.The instructor is absolutely passionate about teaching and you'll find the lessons engaging and ultimately rewarding.

Course Curriculum

The transformer
Q33 The 200.-turn primary coil of a transformer is connected to a 120-volt line. How many turns must the secondary coil of the transformer have if it is to provide 240 volts? [Assume 100% efficiency.]
Q34 A transformer plugged into a 120-volt household electrical outlet is used to operate a 12V doorbell. What is the ratio of the number of turns in the primary coil to the number of turns in the secondary coil of the transformer?
Q35 A 100% efficient transformer has an 800.-turn primary coil connected to 120-volt alternating current source. If the secondary coil has 400 turns, what is the voltage induced in the secondary coil?
Q36 The diagram below shows a step-up transformer having a primary coil with two windings and a secondary coil with four windings. When a potential difference of 12V is applied to the primary coil, what is the current in an 8.0-ohm resistor?
Q37 The transformer on a power pole steps down the voltage from 10,800 volts to 120. volts. If the secondary coil contains 360 turns, how many turns are on the primary coil?
Q38 When a 12-volt potential difference is applied to the primary coil of a transformer, an 8.0-volt potential difference is induced in the secondary coil. If the primary coil has 24 turns, how many turns does the secondary coil have?
Q39 A transformer has 150 turns of wire in the primary coil and 1,200 turns of wire in the secondary coil. The potential difference across the primary coil is 110 volts. What is the potential difference induced across the secondary coil?
Q40 A transformer is designed to step 220 volts up to 2,200 volts. There are 200 turns on the primary coil. How many turns are there on the secondary coil?
Q41 In order for a transformer to function, its primary and secondary coils must
Q42 An ideal transformer has a current of 2.0 amperes and a potential difference of 120 volts across its primary coil. If the current in the secondary coil is 0.50 ampere, the potential difference across the secondary coil is
Q42 explanation
Q43 In a transformer, two coils of wire are wound around a common iron core. To operate properly, the transformer requires
Q44 The primary coil of an operating transformer has 200 turns and the secondary coil has 40 turns. This transformer is being used to
Q45 Which arrangement may be used to step up a voltage?
Q46 The diagram shows a working transformer. Which statement is correct?
Q47 A transformer is to be used to produce a 6 V output from a 24 V input. What are suitable numbers of turns for coil X and for coil Y?
Q48 A transformer is to be used to provide a 10 V output from a 100 V supply. What are suitable numbers of turns for the primary coil and for the secondary coil?
Q49 A transformer has 50 turns on its primary coil and 100 turns on its secondary coil. An alternating voltage of 25.0 V is connected across the primary coil. What is the voltage across the secondary coil?
Q50 The diagram shows a transformer connected to a 240 V a.c. supply. What is the potential difference across the secondary coil of the transformer?
Q51 A transformer has 15 000 turns on its primary coil and 750 turns on its secondary coil. Connected in this way, for what purpose could this transformer be used?
Q52 The diagram shows a transformer operating a door bell The mains supply of 240 V is connected to the transformer. The bell has a resistance of 8.0 Ω and the output voltage from the transformer is 12 V. What is the current drawn from the mains supply?
Q53 An alternating current flows through coil P. Coil Q is connected to a C.R.O. on which a sinusoidal trace appears. What happens to the trace if P and Q are linked by a soft-iron core?
Q54 The graph shows the voltage input to a step-down transformer. Which diagram shows the voltage output from the transformer?
Q55 Electric power cables transmit electrical energy over large distances using a high voltage, alternating current. What are the advantages of using a high voltage and of using an alternating current?
Q55 explanation