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Electric Circuits
A voltmeter is connected in parallel with a variable resistance R which is in series with an ammeter and a cell. For one value of R, the meters read 0.3A and 0.9V. For another value of R the readings are 0.25A and 1.0V. What is the internal resistance of the cell?
1. 0.5ohm
2. 2 ohm
3. 1.2ohm
4. 1ohm
1. 0.5ohm
2. 2 ohm
3. 1.2ohm
4. 1ohm
Electric Circuits
Two batteries of emf and internal resistance connected in series with each other and with an external load resistor. The current is 3 A. When the polarity of one battery is reversed the current becomes 1 A. The ratio of the emfs of the two batteries is?
1) 2.5
2) 2
3) 1.5
4) 1
1) 2.5
2) 2
3) 1.5
4) 1
Electric Circuits
Consider a two-input NOR gate. Which of the following inputs to this NOR gate will give an output of Logic 1?
1. Logic 0, Logic 0
2. Logic 0, Logic 1
3. Logic 1, Logic 0
4. Logic 1, Logic 1
1. Logic 0, Logic 0
2. Logic 0, Logic 1
3. Logic 1, Logic 0
4. Logic 1, Logic 1
Electric Circuits
Consider a two-input NAND gate. Which of the following inputs to this NAND gate will give an output of Logic 0?
1. Logic 0, Logic 0
2.Logic 1, Logic 1
3. Logic 1, Logic 0
4. Logic 0, Logic 1
1. Logic 0, Logic 0
2.Logic 1, Logic 1
3. Logic 1, Logic 0
4. Logic 0, Logic 1
Electric Circuits
Consider a D-type flip-flop.
The input to D changes from a logic 1 to a logic 0 just after the falling edge of the clock.
Qn=1 at the time D changes. Which of the following is true?
1.at the falling edge of the clock, Qn+1=0
2.at the falling edge of the clock, Qn+1=1
3.at the rising edge of the clock, Qn+1=0
4.at the rising edge of the clock, Qn+1=1
The input to D changes from a logic 1 to a logic 0 just after the falling edge of the clock.
Qn=1 at the time D changes. Which of the following is true?
1.at the falling edge of the clock, Qn+1=0
2.at the falling edge of the clock, Qn+1=1
3.at the rising edge of the clock, Qn+1=0
4.at the rising edge of the clock, Qn+1=1
Electric Circuits
Consider a J-K flip-flop. J=1, K=1. Which of the following is true?
1.at the falling edge of the clock, Qn+1 is the same logic state as Qn
2.at the falling edge of the clock, Qn+1 is the opposite state of Qn
3.at the rising edge of the clock, is the same logic state as Qn
4.at the rising edge of the clock, Qn+1 is the opposite state of Qn
1.at the falling edge of the clock, Qn+1 is the same logic state as Qn
2.at the falling edge of the clock, Qn+1 is the opposite state of Qn
3.at the rising edge of the clock, is the same logic state as Qn
4.at the rising edge of the clock, Qn+1 is the opposite state of Qn
Electric Circuits
You are required to specify the power rating of a resistor, R1, to be used in a car engine management system, so that an order can be placed for the component (resistor).
The resistance required is 2Ω. The maximum current that will be flowing in the resistor will be 10A.
This resistor is only available in the following power ratings - Choose the most appropriate power rating for this resistor for the given application.
1. 2W
2. 20W
3. 120W
4. 250W
The resistance required is 2Ω. The maximum current that will be flowing in the resistor will be 10A.
This resistor is only available in the following power ratings - Choose the most appropriate power rating for this resistor for the given application.
1. 2W
2. 20W
3. 120W
4. 250W
Electric Circuits
In investigating an existing design of a circuit, it was found that a 25Ω resistor disspates 9W.
The engineer decides to put a 12.5Ω resistor in series with this 25Ω resistor.
What is the power dissipation now in the 25Ω resistor with the same supply voltage after the 12.5Ω resistor was added?
(clue - determine what the supply voltage is from the given information. Then you can either use the voltage divider theory to find the voltage now dropped across the 25Ω and then work out the power, or you can calculate the total current now drawn by both resistors and then work out the power across the 25Ω resistor!)
The engineer decides to put a 12.5Ω resistor in series with this 25Ω resistor.
What is the power dissipation now in the 25Ω resistor with the same supply voltage after the 12.5Ω resistor was added?
(clue - determine what the supply voltage is from the given information. Then you can either use the voltage divider theory to find the voltage now dropped across the 25Ω and then work out the power, or you can calculate the total current now drawn by both resistors and then work out the power across the 25Ω resistor!)
Electric Circuits
A diode allows current to flow in one direction only.
Consider the case when the anode is connected to the positive end of a power supply via a resistor and the cathode to the negative terminal of the same power supply.
Which of the following statements is true about the diode for this particular case?
1,The diode is in reverse bias
2.The diode is in Forward bias
3.The diode conducts
4.The diode does not conduct
Consider the case when the anode is connected to the positive end of a power supply via a resistor and the cathode to the negative terminal of the same power supply.
Which of the following statements is true about the diode for this particular case?
1,The diode is in reverse bias
2.The diode is in Forward bias
3.The diode conducts
4.The diode does not conduct
Electric Circuits
A capacitor of value 10 µF is connected in series with a resistor of value 10Ω. Calculate the value of the time constant.
