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

A radioactive substance decays to (1/10)^th of its original value in 56 days. Calculate its decay constant. 

What is alpha decay?

What is beta decay?

A 0.1 H inductor a 25 × 10^-6 F capacitor and a 15 Ω resistor are connected in series to a 120 V, 50 Hz AC source. Calculate the resonant frequency.

If ‘θ’ represents the angle of contact made by a liquid which completely wets the surface of the container then ______.

The disintegration rate of a radio-active sample is 10¹⁰ per hour at 20 hours from the start. It reduces to 5 × 10⁹ per hour after 30 hours. Calculate the decay constant.

From the v - t graph of a particle executing SHM of period T, which following statements is INCORRECT?

If the number of nuclei of a radioactive substance becomes `1/e` times the initial number in 10 days, what is the decay constant of the substance?

Show that the number of nuclei of a radioactive material decreases exponentially with time.

Efficiency of transformer is the ratio of ______.

The half-life of \[\ce{^238_92U}\] undergoing ∝- -decay is 4.5 × 10⁹ years. What is the activity of 1g sample of \[\ce{^238_92U}\]?

Prove that the inductance of parallel wires of length l in the same circuit is given by L = `((mu_0l)/pi) "in" (d/a)` where 'a' is the radius of wire and d is seperation between wire axes.

Define half-life period.

In one mean lifetime of a radioactive element the fraction of the nuclei that has disintegrated is ______. [e is the base of natural logarithm]

The wires which connect the battery of an automobile to its starting motor carry a current of 300 A (for a short time). What is the force per unit length between the wires if they are 70 cm long and 1.5 cm apart? 

The self-inductance of a closely wound coil of 200 turns is 10 mH. Determine the value of magnetic flux through the cross-section of the coil when the current passing through the coil is 4 mA.

What is a transformer?

Derive the equation for a transformer.

The decay constant of radioactive substance is 4.33 x 10^-4 per year. Calculate its half life period.

A seconds pendulum is suspended in an elevator moving with constant speed in downward direction. The periodic time (T) of that pendulum is _______.