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Electronics and Communication Engineering - Electronic Devices and Circuits

Exercise : Electronic Devices and Circuits - Section 6
46.
In the figure, the LED
emits light when both S1 and S2 are closed
emits light when both S1 and S2 are open
emits light when only S1 and S2 is closed
does not Emit light, irrespective of the switched positions
Answer: Option
Explanation:

To emit the light, it is necessary NAND gate output is zero, for NAND O/P zero. Both the I/O must be height. And it is not possible in any case.

47.
A 4 bit ripple counter uses flip flops with propagation delay of 50 ns each. The maximum clock frequency which can be used is
5 MHz
10 MHz
20 MHz
25 MHz
Answer: Option
Explanation:

Time delay = 50 x 4 x 10-9s,

.

48.
An AND gate has two inputs A and B and one inhibit input S. Out of total 8 input states, output is 1 in
1 state
2 states
3 states
4 states
Answer: Option
Explanation:

Only one input, i.e., A = 1, B = 1 and S = 0 gives output 1.

49.
26810 = __________ .
10A16
10B16
10C16
10D16
Answer: Option
Explanation:

10C in hexadecimal = 1 x 162 + 12 = 268 in decimal.

50.
In a JK Master slave flip flop
both master and slave are positively clocked
both master and slave are negatively clocked
master is positively clocked and slave is negatively clocked
master is negatively clocked and slave is positively clocked
Answer: Option
Explanation:

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