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Electronic devices and circuits
1-Dont try to cram or spend more time here just read it fast and cover syllabus then practice MCQ's cheptor of same topic to check your progress. . |
2-Wrong options are also given but dont concentrate there, Right answer is in bold format. |
Q21 ⇒ Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20°C and 32 nA at 50°C. Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10°C rise in temperature. Both A and R are true and R is correct explanation of A [other wrong options] [Discuss in forum] Both A and R are true but R is not a correct explanation of A A is true but R is false A is false but R is true |
Q22 ⇒ If the drift velocity of holes under a field gradient of 100 V/m is 5m/sec. Their mobility is 0.05 [other wrong options] [Discuss in forum] 0.5 50 500 |
Q23 ⇒ The normal operation of JFET is constant current region [other wrong options] [Discuss in forum] constant voltage region both constant voltage and constant current regions either constant voltage or constant current region |
Q24 ⇒ Resistivity of hard drawn copper is more than that of annealed copper [other wrong options] [Discuss in forum] less than that of annealed copper same as that of annealed copper decreasing when temperature increases |
Q25 ⇒ In all metals conductivity decreases with increase in temperature [other wrong options] [Discuss in forum] current flow by electrons as well as by holes resistivity decreases with increase in temperature the gap between valence and conduction bands is small |
Q26 ⇒ The diameter of an atom is 10-10 metre [other wrong options] [Discuss in forum] 10-6 metre 10-15 metre 10-21 metre |
Q27 ⇒ If the reverse voltage across a p-n junction is increased three times, the junction capacitance will decrease by an approximate factor of about 2 [other wrong options] [Discuss in forum] will decrease will increase will increase by an approximate factor of about 2 |
Q28 ⇒ A reverse voltage of 18 V is applied to a semiconductor diode. The voltage across the depletion layer is 18 V [other wrong options] [Discuss in forum] 0 V 0.7 V about 10 V |
Q29 ⇒ When a p-n junction is forward biased the width of depletion layer decreases [other wrong options] [Discuss in forum] the width of depletion layer increases the majority carriers move away from the junction the current is very small |
Q30 ⇒ When a p-n-p transistor is operating in active region, the current in the n region is due to mainly holes [other wrong options] [Discuss in forum] only holes only electrons mainly electrons |
Q31 ⇒ The static characteristic of an adequately forward biased P-n junction is a straight line, if the plot is of __________ Vs → versus log I Vs V [other wrong options] [Discuss in forum] log I Vs log V I Vs log V I Vs V |
Q32 ⇒ The early effect in a BJT is caused by large collector base reverse bias [other wrong options] [Discuss in forum] fast turn on fast turn off large emitter base forward bias |
Q33 ⇒ Compared to bipolar junction transistor, a JFET has high input impedance and low voltage gain [other wrong options] [Discuss in forum] lower input impedance high input impedance and high voltage gain higher voltage gain |
Q34 ⇒ The ratio of diffusion constant for hole DP to the mobility for holes is proportional to T [other wrong options] [Discuss in forum] T2 1/T T3 |
Q35 ⇒ In a piezoelectric crystal, application of a mechanical stress would produce electric polarization in the crystal [other wrong options] [Discuss in forum] plastic deformation of the crystal magnetic Dipoles in the crystal shift in the Fermi level |
Q36 ⇒ Assertion (A): The hybrid p model of a transistor can be reduced to h parameter model and vice versa. Reason (R): Hybrid p and h parameter models are interrelated as both of them describe the same device. Both A and R are true and R is correct explanation of A [other wrong options] [Discuss in forum] Both A and R are true but R is not a correct explanation of A A is true but R is false A is false but R is true |
Q37 ⇒ The most commonly used semiconductor material is silicon [other wrong options] [Discuss in forum] germanium mixture of silicon and germanium none of the above |
Q38 ⇒ Which of the following elements act as donor impurities?
2, 4 and 5 [other wrong options] [Discuss in forum] 1, 2 and 3 1, 2, 4, and 6 3, 4, 5 and 6 |
Q39 ⇒ In intrinsic semiconductor magnitude of free electron and hole concentrations are equal. TRUE [other wrong options] [Discuss in forum] FALSE |
Q40 ⇒ When a voltage is applied to a semiconductor crystal then the free electrons will flow. towards positive terminal [other wrong options] [Discuss in forum] towards negative terminal either towards positive terminal or negative terminal towards positive terminal for 1 μs and towards negative terminal for next 1 μs |
Or |