To reduce the range of voltmeter, its resistance needs to be reduced. A voltmeter has resistance Ro and ranges V. Which of the following resistances when connected in parallel will convert it into a voltmeter of range V/n?
nR0
(n+1)R0
(n-1)R
None of these
Two condensers, one of capacity C and the other of capacity C/2, are connected to a V- volt battery, as shown.
The work done in charging fully both the condensers is
CV2
A capacitor of capacitance 5μF is connected as shown in the figure. The internal resistance of the hell is 0.5 Ω. The amount of charge on the capacitor plates is
80μC
40 μC
20 μC
10μC
You are given resistance wire of length 50 cm and a battery of negligible resistance. In which of the following cases is the largest amount of heat generated?
When the wire is connected to the battery directly
When the wire is divided into two parts and both the parts are connected to the battery in parallel.
When the wire is divided into four parts and all the four parts are connected to the battery in parallel.
When only half of the wire is connected to the battery
When the radioactive isotope decays in a series by the emission of three alpha (α) and a beta (β) particle, the isotope X which remains undecay is
N lamps each of resistance r, are fed by the machine of resistance R. If light emitted by any lamp is proportional to the square of the heat produced, prove that the most efficient way of arranging them is to place them in parallel arcs, each containing n lamps, where n is the integer nearest to.
(NRr)3/2
(NRr)1/2
B.
As each is containing n lamps, hence,
The resistance of each arc = nr
Number of arcs = N/n
Total resistance S is given by
If E is the emf of the machine, current entering the arcs is E/(R+S) and in each arc is nE/(R+S)N.
Hence, the current passing through each lamp.
Now heat produced per second in the lamps is
H = NI2
since, light emitted is proportional to H2 therefore, the light produced is maximum when H2 and hence H is maximum or is minimum. Hence, we can write,
This is minimum when or very small or n is closely equal to (NR/r)1/2
Radioactive decay will occur as follows
If a certain mass of radon (Rn = 220) is allowed to decay in a certain container; then after 5 minutes the element with the greater mass will be
radon
polonium
lead
bismuth
White light is used to illuminate two slits in Young's double slit experiment. The separation between the slits is b and the screen is at a distance d (>>b) from the slits. At a point on the screen directly in front of one of the slits, which wavelengths are missing?
The wavelength λ of a photon and the de-Broglie wavelength of an electron have the same value. Find the ratio of the energy of a photon to the kinetic energy of an electron in terms of mass m, the speed of light c and Planck constant.
A nucleus has mass represented by m (A,Z). If mp and mn denote the mass of proton and neutron respectively and BE the binding energy (in MeV) then.