Question of the day

Q- Two very long coaxial cylindrical conductors with the inner cylinder has a radius a = 2 cm and caries a total current of I₁ = 1.2 A in the positive z-direction and the outer cylinder has an inner radius b = 4 cm, outer radius c = 6 cm and carries a current of I₂ = 2.4 A in the negative z-directio...

Q- A circuit contains a parallel combination of two resistors of resistance R each  and three capacitors with capacitance C each in series with a V volt battery. Initially there is no charge on any capacitor. The switch is closed at t = 0. 

(a) What is the charge on the first capacitor plat...

Q- Neutron stars are extremely dense objects with a mass comparable to the mass of the sun but a radius of only several thousand meters. Consider a neutron star of mass M = 1.99*10³⁰ kg and a radius of R = 10.2 km.

(a) What is the gravitational acceleration near the surface of the star?

(b) If an...

Q- A uniform circular thin disc of mass 4m and radius R is attached with a particle of mass m at point A on its circumference. The loaded disc is free to rotate about a horizontal axis which is tangential to the disc at the point B, where AB is a diameter. The disc is released from rest with AB at a...

Q- A thin film of index of refraction of 1.35 is placed over a glass plate of refractive index 1.67. White light incident on the film and it is noticed that only two visible colors in the reflected light are 400 and 525 nm. Determine the thickness of the film.

Solution:

Q- A cylinder of hydrogen, 2 m in height and with a 25 cm diameter, is dropped and develops a crack of size 0.1 mm2. The gas is stored at 10 bar absolute pressure. Estimate how long it takes for half the contents to leak out. Explain your reasoning and assumptions.

Solution:

Q- An electron in Chromium (Z=24) moves from the n="2" to the n="1" state without emitting a photon. Instead, the excess energy is transmitted to an outer electron (n=4 state), which is emitted. This is called an Auger Electron. Using ionization considerations, calculate the kine...

Q- A solid right circular cylinder of mass 5kg and diameter 12cm is suspended by a spring of constant K= 2 N/cm-1  and hangs partially submerged in a large water body with its axis vertical. Find the period of small vertical oscillations. Neglect viscosity and surface tension of water.

Q- During the time interval between t = 0 and t = 17 s, the total charge that crossed a plane across a wire at time t is given by 16 (1 - e^-t/5.8), where t is in seconds. What is the maximum value of the current? What is the current at t = 5.8 s? 

Solution: