# Competitive Exams: Physics MCQs (Practice-Test 30 of 35)

1. The hypercharge Y of an elementary particle is equal to

1. Q, the charge on the particle

2. B, the Baryon number

3. S, the strangeness quantum number

4. B + S

2. The particle W-was predicted in 1963 as member of the Baryon decoupled and discovered in 1964. Its spin J, isospin I and strangeness quantum number S are J I S

1. ½ 0 − 1

2. 3/2 1 − 2

3. 3/2 0 − 3

4. 3/2 0 + 3

3. Given that Eb1 = 250 V at Ec1 = -50V, Eb2 = 180 V at Ec2 = -30 V and plate current being kept the same, the of a triode is

1. 6

2. 5

3. 3.5

4. 5.5

4. Pure silicon is simultaneously doped with boron to a concentration of 1020 atoms per cubic centimeter and with phosphorus to a concentration of 7 × 1019 atoms per cubic centimeter. The number of holes per unit volume of silicon will be approximately

1. 1020

2. 17 × 1019

3. 7 × 1019

4. 3 × 1019

5. The output characteristic of a bipolar junction transistor is shown in the following diagram, in the diagram, the Active region A, cut-off region B, Saturation region C and Burnout region D are respectively the regions labeled as

1. n/a

2. N/A

3. N/A

4. N/A

6. Which one of the following diagram correctly indicates the widths of the space charge regions of the given pn junction?

1. n/a

2. N/A

3. N/A

4. N/A

7. An electrical property (X) of a solid varies with temperature (T, in Kelvin) as shown schematically in the given diagram. This is an illustration of the variation with temperature of the

1. resistivity of pure silicon

2. resistivity of pure annealed cope

3. conductivity of pure silicon

4. conductivity of p-type silicon

8. The current (J) voltage (V) characteristic of a p-n diode is as shown in the given figure. The knee voltage is at the point labeled

1. C

2. A

3. O

4. B

9. Match List-I with List-II and select the correct answer.

 List-I List-II Emitter-base junction current Base current Emitter-Collector current Base-Collector Driff current Diffusion current Recombination junction current current
• A
• B
• C
• D
• 1
• 2
• 3
• 4
• 1
• 3
• 2
• 4
• 2
• 3
• 1
• 4
• 3
• 2
• 4
• 1
10. The number 6.25 in the decimal notation, when converted to the binary notation will read as

1. 110.100

2. 101.010

3. 110.010

4. 101.001