c=3x108 m/sec . speed of light e=1.6×10-19C-elementary charge Ho=4×10-7Tm/A -Per
ID: 1415576 • Letter: C
Question
c=3x108 m/sec . speed of light e=1.6×10-19C-elementary charge Ho=4×10-7Tm/A -Permeability of the free space E,-8.85 × 10-12C2/(Nm*) -Permittivity of the free space k(kilo)= 103 M(mega )=106 G(giga)=109 m(mili )=10-3 (micro)=10-6 n(nano)=10-9 1. A transformer has 150 turns on the primary and 20 turns on the secondary. 100 V and 10 Amps in the primary coil will be changed to A. 13.3 V and 1.33 A B. 13.3 V and 10 A C. 13.3 V and 75 A D. 750 V and 1.33 A E. 750 V and 75 A 2. The time constant of a RL circuit is 100 sec. If the resistance is 200 , what is the value of the inductance in the circuit? A. 20.0 mH B. 22.5 mlH C. 31.7 mH D. 49.3 mH E. 317 mH 3. A RLC series circuit is driven by a sinusoidal voltage source with a frequency f. Which statement is TRUE? A. At resonance, X>Xe and the current lags the voltage B. The resonance frequency fdepends on R, L, and C. C. At resonance, the impedance of the circuit is the largest. D. At resonance, the current through the circuit is the largest. E. There are several possible resonance frequencies.Explanation / Answer
1 ans
Np=150 ,Ns=20 Vp=100 v Ip=10 A
this concept belongs to the alternating current
Vp/vs=Np/Ns
100/vs=150/20
Vs=13.33 V
the current
Ip/Is=Ns/Np
10/Is=20/150
Is=1500/20=75 A
the correct option is C
2 ans
time constant =100*10^-6 sec
resistance R=200 ohms
3 ans
the XL>Xc as the current lags the voltage
so the correct option is A
4 ans
dI/dt=3 A/s
emf e=4.5 *10^-3 V
the inductance L=e/(di/dt)=4.5*10^-3/3=1.5*10^-3 H
the correct option is B
5 ans
resistance R1=10 ohms
frequency f1=1000 Hz
frequency f2=100
we know the relation b/w resistance and frquency
R1/R2=f1/f2
10/R2=1000/100
R2=1 oms
the correct option isC
6 ans
the resistance R=100 ohms
inductance L=20*10^-3H
resonant frquency f=1 kHz
the resonant frequency f=1/2*pi*[LC]^1/2
1000=1/2*3.14[20*10^-3 C]^1/2
[20*10^-3*C]^1/2=1.6*10^-4
20*10^3*C=2.56*10^-8
C=0.128*10^-5 F
the correct option is A
7 ans
inductance L=900**10^-3 H
frequency f=25 hz
impedance Z=400
therefore the impedance Z=[R^2+w^2L^2]^1/2
400^2=R^2+(2*3.14*25*900*10^-3)^2
16*10^4=R^2+19965.7
160000-19965.7=R^2
the resistance R=374.2 ohms
the correct option is C
8 ans
the potential energy is directly proportional to the inductance ,inversely proportional to the current
so increasing the inductance by a factor 5 reduceing the current by a factor 5
so the correct option is C
9 ans
capacitance C=5*10^-6 F
e.m.f E=100 v
inductance =0.5 *10^-3 H
now we the angular frequency w=1/[LC]^1/2
=1/[0.5*10^-3*5*10^-6]^1/2
=2*10^4 rad/s
the p.d across the C=>vc=I(1/wc)
100=I(1/2*10^4*5*10^-6))
I=10 A
the correct option is D
10 ans
inductance L=40 mH
resistance R=2 ohms
emfE=20 V
the circuit current I=E/R[1-e^-1]
=[20/2]*0.632 =6.32 A
the correct option is A
11 ans
the resistance R=4 ohms
the capacitive reactance Xc=7 ohms
the inductance reactance XL=8 ohms
the phase shift = tan^-1{[XL-Xc]/R}
=tan^-1{[8-7]/4}
=14°
the correct option is E
12 ans
power P=150 W
voltage V=75
basing on joules law=>power=vI
150=75i
i=2 A
the corret option D
13 ans
voltage V=12 v
frequency f=60 Hz
angular frequency w=2*3.14*60=376.8 rad/s
Irms=2.4 A
the current I=3.4 A
basing on alternating current =>V=IXL
12=3.4*376.8*L
L=9.4 mH
the correct option is D
14 ans
15 ans
the refractive index of water n=1.33
the criital angle i=sin^-1[1/n]=sin^-1[1/1.33]=45.12°
the correct option is B
16 ans
basing depresion of prism
yellow
the correct option is C
17 ans
thickness x-1 cm
time t=0.05*10^-9 sec
basing on the light =>time =xµ/c
0.05*10^-9*3*10^8=1*10^-2*µ
µ=1.5
the correct option is E
18 ans
refractive index µ=1.75
incident angle i=30
the refractive index = sini/sinr
1.75=sin 30/sin r
r=16.6°
the correct option is A
19 ans
wavelength =594 nm
distance from slit to screen D=0.8 m
position of the fringes Y=1.9*10^-2 m
therefore the distance b/w the slits =>d=D(wavelength)/y
=0.8*594*10^-9/1.9*10^-2=250.1*10-7 =0.02501 mm
20 ans
basing on the double reflection of the glass option D is correct
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