46. An example of piezoelectric material is:

1. 1. Corundum

   
   
   

   2. Quartz

   
   
   

   3. BaTiO₃

   
   
   

   4. All of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Quartz is an example of piezoelectric material.

   Correct Option: B

   Quartz is an example of piezoelectric material.

---

47. Thermoplastic and thermoset polymers differ in:

1. 1. Glass transition temperature

   
   
   

   2. Thermal behaviour

   
   
   

   3. Mechanical behaviour

   
   
   

   4. All of the above

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Thermoplastic and thermoset polymers differ in Thermal behaviour.

   Correct Option: B

   Thermoplastic and thermoset polymers differ in Thermal behaviour.

---

---

48. Materials which are good conductors of both heat and electricity are:

1. 1. Metals

   
   
   

   2. Ceramics

   
   
   

   3. Polymers

   
   
   

   4. None of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   Materials which are good conductor of heat and electricity are metals.

   Correct Option: A

   Materials which are good conductor of heat and electricity are metals.

---

49. High frequency amplifier use transformers with :

1. 1. alnico core

   
   
   

   2. ferrite core

   
   
   

   3. iron core

   
   
   

   4. none of these

   
   
   

---

1. View Hint View Answer Discuss in Forum

   High frequency amplifiers use transformers with ferrite core.

   Correct Option: B

   High frequency amplifiers use transformers with ferrite core.

---

---

50. E_g of a semiconductor:

1. 1. increases with temperature

   
   
   

   2. is invariant with temperature

   
   
   

   3. decreases with temperature

   
   
   

   4. All of the above

   
   
   

---

1. View Hint View Answer Discuss in Forum

   E_g i.e. band gap of a semiconductor decreases with temperature.

   Correct Option: C

   E_g i.e. band gap of a semiconductor decreases with temperature.

---