Question 11 : Find the expression for the ripple factor in terms of duty cycle α for a type A step down chopper
1. √(1-α/α)
2. α²/2
3. √α/2
4. √(1-α)
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Question 12 : The load emf E must be reversed for
1. first and second quadrant operation
2. third quadrant operation
3. fourth quadrant operation
4. both third and fourth quadrant operation
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Question 13 : If a step up chopper's switch is always kept off then (ideally)
1. Vo = 0
2. Vo = ∞
3. Vo = Vs
4. Vo > Vs
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Question 14 : For a type E chopper operating in the first quadrant, find the expression for average output voltage.
1. Vs
2. E - Ldi/dt
3. 0
4. E + Ldi/dt
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Question 15 : Find the output voltage for a step-up chopper when it is operated at a duty cycle of 50 % and Vs = 240 V.
1. 240 V
2. 480 V
3. 560 V
4. 120 V
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Question 16 : A type C chopper can operate in
1. Ist and IInd quadrants
2. IInd and IIIrd quadrants
3. Ist, IInd and IIIrd quadrants
4. all the four quadrants
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Question 17 : In the current limit control method, the chopper is switched off when
1. load current reaches the lower limit
2. load current reaches the upper limit
3. load current falls to zero
4. none of the mentioned
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Question 18 : A step down chopper has Vs = 230 V and R = 10 Ω. For a duty cycle of 0.4, the power taken by the chopper is 2097 Watts. Find the chopper efficiency. Take the voltage drop across the chopper switch as 2 V.
1. 98 %
2. 89.96 %
3. 99.14 %
4. 96.54 %
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Question 19 : For the type E chopper to be operated in the fourth quadrant
1. only one switch is operated
2. two switches are operated
3. three switches are operated
4. all the switches are operated
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Question 20 : In a type-D chopper
1. current can flow in both the directions of the load
2. current cannot flow in both the directions of the load
3. voltage can only be positive
4. voltage can only be negative
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