Question: Q. 3. (i) In the following diagram ’ S ’ is a semiconductor. Would you increase or decrease the value of R to keep the reading of the ammeter A constant when S is heated? Give reasôn for your answer.

(ii) Draw the circuit diagram of a photodiode and explain its working. Draw its I/V characteristics. U] [OD III 2017]

Show Answer

Solution:

Ans. (i) Correct Choice of R ….. 1/2 Reason ….. 1/2 (ii) Circuit Diagram ….. 1 Working ….. 1/2 I- V characteristics ….. 1/2 (i) R would be increased. ….. 1/2 Resistance of S (a semiconductor) decreases on heating. ….. 1/2

(ii) Photodiode diagram

1

When the photodiode is illuminated with light (photons) (with energy ( hv ) greater than the energy gap (Eg) of the semiconductor), then electronhole pairs are generated due to the absorption of photons. Due to junction field, electrons and holes are separated before they recombine. Electrons are collected on n-side and holes are collected on p-side giving rise to an emt.

1/2

When an external load is connected, current flows. IV Characteristics of the diode :

[CBSE Marking Scheme 2017]



विषयसूची

जेईई के लिए मॉक टेस्ट

एनसीईआरटी अध्याय वीडियो समाधान

दोहरा फलक