Addition of 0.3 to 4.5% silicon to iron __________ the electrical resistivity of iron.

Silicon devices can be employed for a higher temperature limit (190°C to 200°C) as compared to germanium devices (85°C to 100°C). With respect to this, which of the following are incorrect? 1) Higher resistivity of silicon 2) Higher gap energy of silicon 3) Lower intrinsic concentration of silicon 4) Use of silicon devices in high-power applications Select the correct answer using the code given below:

A

1, 2 and 4

B

1, 2 and 3

C

1, 3 and 4

D

2, 3 and 4

Mr.Rohan while helping the students of Class IV in adding and subtracting fractions observed that several students are not able to complete the addition of two improper fractions. He gave a small test with questions from the addition of proper fractions (one item of addition of two similar fractions, three items from the addition of proper and improper fractions, and four items from the addition of improper fractions). He analyzed the responses of each student and found that nearly 45% of students were not clear in adding proper with improper fractions which were affecting their performance in adding two improper fractions. He, therefore, focused on developing the understanding of improper fractions and their addition with proper fractions after which he proceeded to teach the addition of two improper fractions. Which kind of assessment is depicted by this situation?

A

Assessment OF Learning

B

Assessment for Learning

C

Assessment AS Learning

D

Assessment by learning

The electrical resistivity of the material of a conductor is ρ. If its length is doubled and area of cross-section is tripled, then its electrical resistivity will be

A

ρ

B

2ρ

C

3ρ

D

4ρ

Consider the following statements: 1. Dynamic cone penetration test for site investigation is based on the principle that elastic shock waves travel in different materials at different velocities. 2. Electrical resistivity method of subsurface investigation is capable of detecting only the strata having different electrical resistivity. 3. In-situ vane shear test is useful for determining the shear strength of very soft soil and sensitive clays and is unsuitable for sandy soil. Which of these statements is/are correct?

A

1 and 2

B

2 and 3

C

1 and 3

D

2 alone

For better resistance welding, the metal must have
P. high electrical resistivity and low melting point
Q. high thermal conductivity
R. high electrical resistivity and high melting point
S. low thermal conductivity

A

P, Q

B

P, S

C

R, Q

D

R, S

Variation of electrical resistivity $$\rho $$ with temperature T of three solids is sketched (on different scales) in the figure, as curves P, Q and R.
Which one of the following statements describes the variations most appropriately?
Solid State Physics mcq question image

A

P is for a superconductor and R for a semiconductor

B

Q is for a superconductor and P for a conductor

C

Q is for a superconductor and R for a conductor

D

R is for a superconductor and P for a conductor

Match the following Device Conversion of Energy (a) Windmill (i) Chemical Energy to electrical energy (b) Bulb (ii) Kinetic Energy to Electrical Energy (c) Electrical Cell (iii) Sound Energy to Electrical energy (d) Microphone (iv) Electrical Energy to Light Energy

A

(a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)

B

(a) - (ii), (b) - (iv), (c) - (i), (d) - (iii)

C

(a) - (ii), (b) - (iii), (c) - (i), (d) - (iv)

D

(a) - (iii), (b) - (ii), (c) - (iv), (d) - (i)

In the electrical resistivity method, the unit of resistivity is ohms-cm.

A

True

B

False

What does hydropower change A. Kinetic energy to electrical energy B. Mechanical energy from electrical energy C. Chemical energy to electrical energy D. Wind energy to electrical energy

A

C

B

C

D

A

একটি ত্রিভুজের তিনটি কোণের অনুপাত 3ঃ 4ঃ5 হলে, কোণ তিনটির মান কত?

A

৪৫° ৬০° ৭৫°

B

৩০° ৬০° ৯০°

C

৬০° ৯০° ৩০°

D

৯০° ৪৫° ৪৫°

Addition of 0.3 to 4.5% silicon to iron __________ the electrical resistivity of iron.

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