HSC Science (Electronics) 12th Standard Board Exam - Maharashtra State Board Question Bank Solutions for Physics

When does a system lose energy to its surroundings and its internal energy decreases? 

A system releases 100 kJ of heat while 80 kJ of work is done on the system. Calculate the change in internal energy.

Explain given cases related to energy transfer between the system and surrounding –

1. energy transferred (Q) > 0
2. energy transferred (Q) < 0
3. energy transferred (Q) = 0 

Explain the different ways through which the internal energy of the system can be changed. 

One gram of water (1 cm³) becomes 1671 cm³ of steam at a pressure of 1 atm. The latent heat of vaporization at this pressure is 2256 J/g. Calculate the external work and the increase in internal energy. 

A cylinder containing one gram molecule of the gas was compressed adiabatically until its temperature rose from 27°C to 97°C. Calculate the work done and heat produced in the gas (𝛾 = 1.5).

derive the relation between the change in internal energy (∆U), work is done (W), and heat (Q). 

State law of length.

What are forced vibrations? 

Show that even as well as odd harmonics are present as an overtone in modes of vibration of the string. 

What are Secondary sources? State Huygens’ Principle.

The SI unit of the potential gradient is ______  

When the null point is obtained in the potentiometer, the current is drawn from the ______  

If the potential gradient of a wire decreases, then its length ______  

The instrument which can measure terminal potential difference as well as electromotive force (emf) is ______ 

What is the SI unit of potential gradient?

State any one use of a potentiometer.

A voltmeter has a resistance of 100 Ω. What will be its reading when it is connected across a cell of emf 6 V and internal resistance 20 Ω? 

What are the disadvantages of a potentiometer over a voltmeter?

A cell of e.m.f 1.5V and negligible internal resistance is connected in series with a potential meter of length 10 m and the total resistance of 20 Ω. What resistance should be introduced in the resistance box such that the potential drop across the potentiometer is one microvolt per cm of the wire?