where,
E = applied e.m.f. = 110 V
V = back e.m.f. = 100 V
R = resistance of armature and
I = current
We have,
Mechanical power, P = EI-I2R = VI
or EI-I2R = VI ...(2)
Putting the value E and Vin eqn. (2), we get
⇒ 110I-I2R = 100xI
or 100 -IR = 100
IR = 110- 100= 10
We know that,
P = VI ...(3)
where
P = 5 KW = 5 x 103 W
⇒ 100 x I = 5 x 103
or I =
Also we know that,
V = IR
Hence,
Current I = 50 A and
Resistance (R) = 0.2 Ω
Derive the formula for angular magnification of a compound microscope, when the final image is formed at least distance of distinct vision. Draw the required ray diagram.
Give the expression for the velocity of electron in the first orbit of Hydrogen atom and for the radius in the ground state of Hydrogen atom.
Hence derive the expression for the kinetic energy of the electron.
In Millikan’s oil drop experiment, a charged oil drop of density 880 kg/m3 is held stationary between two parallel plates 6.0 mm apart at a potential difference of 1000 volts. When electric field E is switched off, the oil drop was observed to fall a distance of 2.0 mm in 35.7 seconds. [4]
(i) Find the radius of oil drop.
Given :
η for air = 1.8 x 10-5 poise
Density of air = 1.29 kg/m3
Use g = 9.81 m/s2