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turns on the secondary. If the 1) An ideal transformer has a coil with 2000 turn

ID: 1794488 • Letter: T

Question

turns on the secondary. If the 1) An ideal transformer has a coil with 2000 turns voltage reading on the secondary is 400V what is the voltage reading on the primary? on the primary and 8000 a) 1600V b) 16V c) 250V d) 100V e) 400V 2) A transformer has Np: 1200 , Ns=100, , vp-240V, Vs= 19V, lp:12mA and efficiency 90%. What is the value of the power Ps on the secondary? a) 2592 W b) 2.592 W )2280 W d) 2280 mW e) 0.216 W 3) A Transformer with efficiency 80% has 150 turns on the primary and 300 turns on the secondary. the primary, the voltage is Vp- 3V and the current Ip-0.01A. On the secondary the voltage is Vs-4V much is the current on the secondary? On a) 0.024 A b) 0.0024A c)0.0075 A d) 0.006 A e) 0.005A 4) What happens to the output (secondary) power when the load resistance becomes very large (Choose the best description) a) Secondary power goes to zero because Is goes to zero b) Secondary power goes to zero because Vs goes to zero c) Secondary power goes to 1 d) Secondary power goes to same value as primary power e) Primary and secondary power go to zero 5) A transformer has Np 2400, Ns-200, Vp-480V, Vs 36V, Ip-50mA, Is-560mA. What is the efficiency of the transformer? a) 0.706 b) 0.917c)1 d) 0.84 e) 1.19d) 1.41

Explanation / Answer

Question 1) Given , Np = 2000 , Ns = 8000

Vs = 400 V

For a transformer ,

Vs/Vp = Ns/Np

400/Vp = 8000/2000

Vp = 400/4 = 100 V

Vp = 100 V

Therefore , answer ) option d) 100 V