Write the current ratio formula.

Write the current ratio formula. b) Write the turns ratio formula. c) Write the voltage ratio formula. d) Is the number of secondary turns in a step-up transformer higher than the number of primary turns? True or False. e) Is the number of secondary turns in a step-down transformer lower than the number of primary turns? True or False. Questions f-i are based on the following drawing: s = 1A Primary: 60V (AC) Secondary: f) The value of the primary current is equal to _ amps. 10:1 turns ratio g) The secondary voltage is equal to volts. h) The total power in the primary winding equals __ watts. i) The input winding of a transformer is called the

The Correct Answer and Explanation is:

Here are the correct answers and detailed explanations:

a) Current Ratio Formula: IpIs=NsNp\frac{I_p}{I_s} = \frac{N_s}{N_p}Is​Ip​​=Np​Ns​​

Where:

• IpI_pIp​ is the primary current
• IsI_sIs​ is the secondary current
• NpN_pNp​ is the number of turns in the primary coil
• NsN_sNs​ is the number of turns in the secondary coil

This formula shows that current is inversely proportional to the number of turns. More turns mean less current, and fewer turns mean more current.

b) Turns Ratio Formula: NpNs=VpVs\frac{N_p}{N_s} = \frac{V_p}{V_s}Ns​Np​​=Vs​Vp​​

This equation relates the number of turns in the primary and secondary windings to the voltages across them. A transformer changes voltage depending on this turns ratio.

c) Voltage Ratio Formula: VpVs=NpNs\frac{V_p}{V_s} = \frac{N_p}{N_s}Vs​Vp​​=Ns​Np​​

Where:

• VpV_pVp​ is the primary voltage
• VsV_sVs​ is the secondary voltage

Voltage is directly proportional to the number of turns. More turns result in higher voltage.

d) True.
In a step-up transformer, the secondary winding has more turns than the primary to increase voltage.

e) True.
In a step-down transformer, the secondary winding has fewer turns than the primary to reduce voltage.

Based on the drawing:

• Given:
  • Primary voltage Vp=60VV_p = 60VVp​=60V
  • Turns ratio Np:Ns=10:1N_p : N_s = 10 : 1Np​:Ns​=10:1
  • Secondary current Is=1AI_s = 1AIs​=1A

f) Primary Current = 0.1 A

Use the current ratio formula: Ip1=110⇒Ip=0.1 A\frac{I_p}{1} = \frac{1}{10} \Rightarrow I_p = 0.1 \, \text{A}1Ip​​=101​⇒Ip​=0.1A

g) Secondary Voltage = 6 V

Use the voltage ratio formula: VpVs=NpNs=10⇒60Vs=10⇒Vs=6 V\frac{V_p}{V_s} = \frac{N_p}{N_s} = 10 \Rightarrow \frac{60}{V_s} = 10 \Rightarrow V_s = 6 \, \text{V}Vs​Vp​​=Ns​Np​​=10⇒Vs​60​=10⇒Vs​=6V

h) Power = 6 W

Power is conserved in an ideal transformer: P=Vs×Is=6×1=6 WP = V_s \times I_s = 6 \times 1 = 6 \, \text{W}P=Vs​×Is​=6×1=6W

Also: P=Vp×Ip=60×0.1=6 WP = V_p \times I_p = 60 \times 0.1 = 6 \, \text{W}P=Vp​×Ip​=60×0.1=6W

i) Input Winding = Primary

The input winding of a transformer is called the primary winding, as it receives the incoming electrical energy.

These relationships show the importance of understanding how voltage, current, and number of turns interact in a transformer.