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

Calculate the de-Broglie wavelength of an electron moving with one-fifth of the speed of light.Neglect relativistic effects. (`h = 6.63 xx 10^(-34)` J.s, c= `3xx10^8`m/s, mass of electron = `9 xx 10^(-31) kg)`

An electron of energy 150 eV has wavelength of 10^-10m. The wavelength of a 0.60 keV electron is?

Answer in brief:

What is a perfect blackbody? How can it be realized in practice?

During refrigeration cycle, heat is rejected by the refrigerant in the ______.

A gas contained in a cylinder surrounded by a thick layer of insulating material is quickly compressed has there been a transfer of heat?

Answer in brief:

A gas contained in a cylinder surrounded by a thick layer of insulating material is quickly compressed has work been done?

A resistor of 500 Ω and an inductance of 0.5 H are in series with an AC source which is given by V = `100 sqrt2` sin (1000 t). The power factor of the combination is ______.

In a series LCR circuit, the phase difference between the voltage and the current is 45°. Then the power factor will be ______.

What is wattles current?

When an AC source is connected to an ideal inductor show that the average power supplied by the source over a complete cycle is zero.

Prove that an ideal capacitor in an AC circuit does not dissipate power

(a) An emf e = e₀ sin ωt applied to a series L - C - R circuit derives a current I = I₀sinωt in the circuit. Deduce the expression for the average power dissipated in the circuit.
(b) For circuits used for transporting electric power, a low power factor implies large power loss in transmission. Explain.

An AC source generating a voltage e = e₀sinωt is connected to a capacitor of capacitance C. Find the expression for the current i flowing through it. Plot a graph of e and i versus ωt.

A light bulb is rated 100W for 220 V AC supply of 50 Hz. Calculate

1. resistance of the bulb.
2. the rms current through the bulb

An AC circuit consists of only an inductor of inductance 2 H. If the current is represented by a sine wave of amplitude 0.25 A and frequency 60 Hz, calculate the effective potential difference across the inductor. (π = 3.142)

Alternating emf of e = 220 sin 100 πt is applied to a circuit containing an inductance of (1/π) henry. Write an equation for instantaneous current through the circuit. What will be the reading of the AC galvanometer connected in the circuit?

A 25 μF capacitor, a 0.10 H inductor, and a 25Ω resistor are connected in series with an AC source whose emf is given by e = 310 sin 314 t (volt). What is the frequency, reactance, impedance, current, and phase angle of the circuit?

A 100 μF capacitor is charged with a 50 V source supply. Then source supply is removed and the capacitor is connected across an inductance, as a result of which 5A current flows through the inductance. Calculate the value of the inductance.

Answer in brief.

What sets the limits on the efficiency of a heat engine?