National Examinations Board (+2)
+2 Science (Class 11 and 12)
Class 12 · NEB 2080 (old course)
Course Title: Physics (Phy)
Full Marks: 75Pass Marks: 27Time: 3 hrs
Candidates are required to give their answer in their own words as far as practicable. The figures in the margin indicate full marks.
Group A
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- 1.8
Answer any four questions in brief:
- a. A voltameter measures current more accurately than an ammeter, why ? [2]
- b. Does the thermoelectric effect obey the law of conservation of energy ? Explain. [2]
- c. Steel is used in making permanent magnets where as soft iron is preferred for making the core of transformer. Why ? [2]
- d. The element of a heater is very hot while the wires carrying current are not. Why ? [2]
- e. How will an electron move in a homogenous magnetic field if the velocity of the electron at the initial moment forms an angle '' with the force lines of the field ? [2]
- f. Why is choke coil preferable to resistor ? [2]
- 2.8
Answer, in brief, any four questions:
- a. Beams of electrons and protons having the same initial K.E. enter normally into an electric field, which beam will be more curved ? Justify. [2]
- b. "Production of X-rays is the inverse phenomenon of photoelectric effect". Justify it. [2]
- c. What is nanotechnology ? Explain. [2]
- d. Why is the mass of a nucleus slightly less than the mass of constituent nucleons ? [2]
- e. What do you mean by energy crisis ? [2]
- f. State Hubble's law and write the significance of Hubble's constant. [2]
- 3.2
Answer, in brief, any one question:
- a. If you are walking on the moon surface, can you hear the cracking sound behind you ? Explain. [2]
- b. What is the threshold of hearing ? Define one bel. [2]
- 4.2
Answer, in brief, any one question :
- a. Explain with proper
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