 # MCQs on Impedance for NEET 2021

Impedance is the total opposition that a circuit, electronic component or the entire system offers to the flow of alternating current or direct current. The impedance is a vector quantity consisting of two scalar quantities. The impedance is the combination of resistance and reactance.

Resistance is the property that opposes the flow of current and reactance opposes the change in current.

Q1: What is the value of input impedance of a quarter-wave line 50 ohm and the load impedance of 20 ohms?

1. 50
2. 20
3. 1000
4. 125

Q2: The value of input impedance for a matched line will be equal to

2. Characteristic impedance
3. Output impedance
4. Zero

Q3: What is the ratio of  characteristic impedance to the input impedance if the ratio of load voltage to the input voltage is given as 5

1. 5
2. 10
3. 25

Q4: The maximum impedance of a transmission line 50 ohm and the standing wave ratio of 2.5 is

1. 20
2. 125
3. 200
4. 75

Q5: What is the normally chosen value of the characteristic impedance of a transmission line?

1. 50
2. 75
3. 50 or 75
4. 100

Q6: What is the value of negative sequence impedance?

1. 1
2. Z
3. Same as positive sequence
4. infinity

Answer: (c) Same as positive sequence

Q7: The standing wave ratio is 4 for a transmission line of 75 ohms. What is the value of the minimum impedance?

1. 75
2. 300
3. 18.75
4. 150

Q8: A transmission line has a voltage of 24 V and a conduction current of 1.2 A. What will its receiving impedance?

1. 25.2
2. 22.8
3. 28.8
4. 20

Q9: What is the value of the characteristic impedance of a transmission line with impedance and admittance of 16 and 9?

1. 25
2. 1.33
3. 0.75
4. 7

Q10: The propagation constant of a transmission line with impedance and admittance of 9 and 16, respectively is

1. 25
2. 144
3. 12
4. 7