Physics Key stage 4 Magnetism Transformer Equations Mr

Physics - Key stage 4 - Magnetism Transformer Equations Mr van Hoek

How a transformer works spot the mistakes ● An d. c. input (direct current) creates a strong magnetic field in the iron coil. ● The primary coil transfers the magnetic field to make it an electromagnet with a changing magnetic field. ● The strong magnetic field is now present in the second coil. ● This strong magnetic field creates a potential difference in the second coil. ● If this is connected to a external circuit, a current will grow. 2

I Do A transformer has 400 turns on the primary coil and 200 turns on the secondary coil. If the primary voltage is 300 V, what will the secondary voltage be? 3

We Do A transformer has 525 turns on the secondary coil. The secondary voltage is 300 V and the primary voltage is 100 V Calculate how many turns are on the primary coil. 4

You Do A transformer has 300 turns on the primary coil, and an input potential difference of 63 V. The output potential difference is 32 V. Determine the number of turns on the secondary coil 5

You Do Transformer Turns on the primary coil A 650 B C 4 2. 5 17 12 46 38 550 83 61 26 350 900 D 6 Input (primary) Turns on the potential secondary coil difference (V) Output (secondary) potential difference (V) E 650 750 F 900 600 4. 7 G 850 100 H 200 750 98

Exam question The diagram below shows the structure of a transformer. The secondary coil produces an output of 12 V. Calculate the number of turns needed on the secondary coil. Show your working. marks] [2 OCR, Specimen, J 249/01 Additional answers and guidance not checked by OCR 7

Exam question Transformers are constructed using wire and an iron core. i) Describe the construction of this transformer. [2] ii) Calculate the output voltage. [2] 8 OCR, June 2017, B 752/02 Additional answers and guidance not checked by OCR

I Do Vp × Ip = Vs × Is A transformer has a primary voltage of 30 V and a primary current of 2 A. If the secondary voltage is 15 V, what will the secondary current be? 9

We Do Vp × Ip = Vs × Is A transformer has a primary current of 40 A. If the secondary voltage is 20 V and the secondary current is 8 A, what will the primary voltage be? 10

We Do Vp × Ip = Vs × Is A National Grid step-up transformer outputs 440, 000 V for transmission across the country, with current of 145 A. The input potential difference to the transformer is 32, 000 V What is the input current to the step-up transformer? 11

You Do Vp × Ip = Vs × Is The primary coil potential difference is 32, 000 V, and the current is 10 A. The secondary coil is mains potential difference, 230 V. What is the current? 12

You Do Transformer A Input potential Input current Output potential Output current difference (V) (A) 15 B C 19 62 D 13 68 88 39 58 85 16 120 61 100 17 150 E 98 F 93 G 60 50 110 H 8 4. 6 23 53 66

Exam question The diagram below shows the structure of a transformer. Explain why there is more alternating current in the secondary coil than in the first. [3] OCR, Specimen, J 249/04 Additional answers and guidance not checked by OCR 14

Bringing the two equation together I Do A transformer with 100 turns on the primary coil and 300 turns on the secondary coil needs to produce an output current of 2. 4 A. What will the input current be? 15

Bringing the two equation together We Do A step-down transformer in a computer power supply has an input of 1. 5 A from the mains and produces 30 A to power the computer. There are 600 turns on the primary coil. How many are there on the secondary coil? 16

Bringing the two equation together You Do A high voltage transmission line to a house has a current of just 2. 5 A, though the output from the step-down transformer supplying the house is 100 A. There are 500 turns on the secondary coil, how many turns are on the primary coil? 17