cet physics full

Transcription

cet physics full
KOTA ACADEMY
RAMKUNJ, SAHYADRI HOUSING SOCIETY, SHANIWAR PETH, KARAD
9423866425
MH-CET / JEE / JEE - Adv. / AIPMT
Date :
Time : 00:45:00Mins
Marks : 50
1.
2.
3.
4.
5.
6.
7.
8.
The work done by the centripetal force in quarter
revolution would be,
a) infinity
b) increases
c) zero
d) decreases
In half period of revolution displacement and the
distance covered is:
a) 2r , πr
b) πr, 2r
c) 2 πr,2r
d) zero, 2 πr
A ball of mass 0.5kg and diameter 8cm rotates in a
horizontal circle at the end of a string of 1.96 m
long. The tension in the string, when the speed of
rotation is 10 revolution in 2 sec. will be
a) 785 N
b) 986 N
c) 585 N
d) 685 N
24
The earth (mass =6.10 kg) revolves round the
sun with an angular velocity of 2×10-7 rad/s in a
circular orbit of radius 1.5 ×108 km in a circular
orbit of radius 1.5×108 km the gravitational force
exerted by the sun in the earth, in Newton, is
a) Zero
b) 18×1025
c) 36×1021
d) 3.6×1018
Gravitational force between two bodies exists
a) When they are in contact only
b) When they are not in contact only
c) Any of the above two cases
d) Can not be predicted
A cylinder full of water is rotating about its own
axis with uniform angular velocity  Then the
shape of free surface of water will be
a) parabola
b) elliptical
c) circular
d) spherical
M.I. of a uniform disc about a central axis is 1
kgm2. It is rotating with an angular velocity of 100
rad/sec. Another identical disc is gently placed on
it so that their centre coincides now these two
move together with the same axis the loss in K.E.
of rotation will be in joules:
a) 2.5 kJ
b) 3.0 kJ
c) 3.5 kJ
d) 4.0 kJ
AB is a stick half of which is wood and the other
half steel. IA is moment of inertia about an axis
TEST ID: 24
PHYSICS
passing through A and perpendicular to the
length. IB is moment of inertia about an axis
passing through B and perpendicular to the length
Then
9.
a) IA = IB
b) IA > IB
c) IB > IA
d) we cannot say
A simple pendulum is suspended from roof of lift.
If lift moves downward with acceleration a then
period of pendulum T = 2 π
10.
11.
12.
13.
14.
𝑙
g
then g' will be:
a) g + a
b) g - a
2
2
d) g
c) 𝑔 + 𝑎
If the rope of the lift breaks , time period of
suspended pendulum in a lift is
a) zero
b) abrupt by increases
c) abrupt by decreases d) infinite
The displacement of a particle performing S.H.M.
is given by x = 10 sin (𝜔𝑡 + 𝛼 ) metre. If the
displacement of the particle is 5 m, then the phase
of S.H.M. is
𝜋
𝜋
a) radian
b) radian
3
6
𝜋
𝜋
c) radian
d) radian
4
2
The spring balance shows wrong readings after
they have been used for a long time because
a) of extension in the spring decreases
b) of extension in the spring is more
c) of the spring looses elastic property and
becomes plastic
d) of lack of internal elastic forces
A wire of length L, radius r when stretched with a
force F changes the length by ℓ. What will be the
change in length of a wire of same material having
length 2L, radius 2r and stretched by a force 2F?
a) ℓ /2
b) ℓ
c) 2 ℓ
d) 4 ℓ
Two soap bubbles of different radii are in
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15.
16.
17.
18.
19.
20.
communication with each other. :
a) Air flows from the larger bubble into the
smal1er one until the two bubbles are of equal
size
b) The size of the bubbles remains the same.
c) Air flows from smaller bubble into the larger
one and the larger bubble grows at the expense
of the smaller one
d) Air flows from larger bubble into the smal1er
one and the smal1er bubble grows at the
expense of the larger one
If two soap bubbles of unequal radii are in
communication with each other , then
a) air flows from the larger bubbles into smaller
bubble until they have the same size
b) the size of the bubbles remains the same
c) air flow from smaller bubbles into larger
bubble and the larger bubble grows in size and
the size of the smaller bubble decreases.
d) air may flow from the smaller bubble into the
larger bubble or from the lager bubble into the
smaller bubble depending upon the
concentration of the soap solution
A drop of water splits up into 64 droplets each of
equal radius of 1 mm. The original droplet is
having a diameter of:
a) 2 mm
b) 4 mm
c) 64 mm
d) 128 mm
The prongs of the tuning fork are filled a little, the
frequency of the tuning fork after filled
a) increases
b) remains constant
c) decreases
d) cannot be predicated
The equation of a sound wave is y = 0.0015 sin
(62.8 x + 316 t). Find the wavelength of this
wave:
a) 0.2 unit
b) 0.1 unit
c) 0.3 unit
d) 0.4 unit
When longitudinal stationary waves are produced
in a medium, then the physical characteristics
changes at antinode is / are
a) density only
b) density and pressure
c) pressure only
d) neither density nor pressure
A tuning fork of frequency of resonants with a
closed organ pipe when the length of the shortest
air columns are a & b respectively The speed of
sound in air is:
f b−a
a) f (a - b)
b)
2
c) 2V (b + a)
d) 2f (b - a)
21. Velocity of a particle in stationary wave is
maximum at
a) antinode
b) node
c) mid way between node and antinode
d) can not be predicted
22. Rice takes longest time to cook:
a) at the sea level
b) in srinager
c) at mount Everest
d) in submarine 100 m below the surface of sea
23. The luminousity of a star is10000 times that of
the sun. If the surface temperature of the sun is
6000 K, then the surface temperature of the star is
a) 8446 K
b) 84860 K
c) 848600 K
d) 60,000 K
24. The average velocity of the gas molecules in a gas
in equilibrium is
a) proportional to square root of temperature
b) proportional to temperature
c) proportional to square of temperature
d) equal to zero
25. The radius of curvature of a plane wavefront
a) is less than that of a spherical wavefront
b) is infinity
c) is equal to the radius of curvature of a
reversing wavefront
d) is slightly more than that of a cylindrical
wavefront
26. According to Huygen's construction which of the
following wavefront does not exists?
a) forward wavefront b) backward wavefront
c) cylindrical wavefront d) can not be predicted
27. In which of the following coloured light limit of
resolution is more :
a) Red
b) Green
c) Yellow
d) Violet
28. Biprism experiment is conducted with a
wavelength of 5000 Å. The distance between the
Virtual sources is 0.2 mm and the micrometer
eyepiece is at a distance of 100 cm from the slits.
The distance between the consecutive bright and
dark band is
a) 1.25 mm
b) 2.5 mm
c) 3.5 mm
d) 0.25 mm
29. Two capacitors of capacitances 10 F and 20 F
are connected in series across a potential
difference of 100V. The potential difference
across each condenser is respectively
a) 66.67 V, 33.33 V
b) 60 V, 40 V
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30.
31.
32.
33.
34.
35.
36.
37.
c) 50 V, 50 V
d) 90 V, 10 V
A dielectric is introduced between thy elements of
the condenser kept at a constant potential
difference. Then the charge on condenser
a) Decrease
b) increase
c) remains unchanged
d) may increase or decrease
A potentiometer wire is 10 m long and has a
resistance of 2 Ω/m. It is connected in series with
a battery of e. m. f. 3 V and a resistance of 10
Ω. The potential gradient along the wire in V/m is
a) 0.01
b) 0.02
c) 0.1
d) 0.2
The internal resistance of an ideal cell is
a) Zero
b) 1 ohm
c) 2 ohm
d) Infinity
When a number of thermocouple are joined in
series, the thermo e. m. f.
a) Decreases
b) Increases
c) Becomes zero
d) Remains same.
A proton is to circulate the earth along the
equator with a speed of 1 × 107 m/s. The
minimum magnetic field which should be created
at the equator for this purpose will be (mp = 1.7 ×
10-27 kg and r = 6.37 × 106m)
a) 1.6 × 10-8 T
b) 2.6 × 10-8 T
c) 3.6 × 10-8 T
d) 4.6 × 10-8 T
The coil of a galvanometer consists of 100 turns
and effective area of 1 square cm. The restoring
couple is 10-8 N-m/radian. The magnetic field
between the pole pieces is 5T. The current
sensitivity of this galvanometer will be (a) p (8)
(c) (d) 1oq,i
a) 5 × 104 rad/ µamp
b) 5 × 10-6 rad/ amp
c) 2 × 10-7 rad/ amp
d) 5 rad/ µamp
A galvanometer of resistance 25 Ω is shunted by
2.5 Ω resistance. The part (fraction) of the total
current that flows through the galvanometer is
given as
IG
1
IG
2
a) =
b) =
I0 11
I0 11
IG
3
IG
4
c) =
d) =
I0 11
I0 11
In hydrogen atom the electrons revolves around
the nucleus 6.8× 1015 times per second in an
orbit of radius 0.53A. Determine its equivalent
magnetic moment(e = 1.6 × 10−19 C)
a) 9.1 × 10−24 Am2
b) 9.3 × 10−24 Am2
−24
2
c) 9.0 × 10 Am
d) 9.6 × 10−24 Am2
38. Curie temperature is particular temperature at
which ferromagnetic material changes to
a) Diamagnetic
b) Nonmagnetic
c) Paramagnetic
d) Antimagnetic
39. An L.C. circuit contains 10 mH inductor and a
2.5μF capacitor the resistance of the circuit is
negligible. The energy stored in the circuit is
completely magnetic at time (in milli
seconds)being measured from the instant when
the circuit is closed
a) 1.57,4.71,7.85
b) 1.57,3.14,4.17
c) 0,1.57,4.71
d) 15.7,47.1,78.5
40. A voltmeter reads V volts in an A.C. circuit then V
is
a) peak value of the voltage
b) peak value of the current
c) r.m.s. value of the current
d) r.m.s. value of the voltage
41. In circuit shown in figure what will be the reading
of a voltmeter and ammeter if a.c. source of 220 V
and 100 Hz is connected?
a) 220 V, 2 A
b) 300 V, 2A
c) 220 V, 2.2A
d) 300 V, 2.2 A
42. The work function for photoelectric effect
a) depends upon the frequency of incident light
b) is same for all metals
c) is different for different metals
d) none of these
43. ln photoelectric effect, the number of
photoelectrons emitted is proportional to
a) intensity of incident beam
b) frequency of incident beam
c) velocity of incident beam
d) none of these
44. If the kinetic energy associated with an electron is
doubled, then its de Broglie wavelength changes
by the factor
a) 2
b) 1/2
c) 2
d) 1 / 2
45. The ratio of the frequencies of the long
wavelength limits of Lyman and Balmer series of
hydrogen is:
a) 4: 1
b) 1: 4
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c) 27: 5
d) 5: 27
46. LASER is and acronym of:
a) Light Analysis of Spontaneous Emission of
Radiation
b) Light Amplification of Spontaneous Emission of
Radiation
c) Light Amplification by Stimulated Emission of
a) 2A
b) 1A
Radiation
c) 0.5A
d) 0.25A
d) Light Analysis by Stimulated Emission of
49. Sky wave propagation is called as shortwave
Radiation.
band (SW) used in:
47. In a half wave rectifier, the r.m.s. value of the a.c.
a) Radio communication
component of the wave is
b) T.V. communication
a) equal to d.c. value
b) more than d.c. value.
c) Satellite communication
c) less than d.c. value. d) zero.
d) Satellite and T.V. communication
48. Current through the battery in the given figure:
50. In the process of modulation , the signals whose
characteristic is changed according to modulating
signals is called as :
a) Modulated signals
b) Analog signals
c) Digital signals
d) Modulating signals
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KOTA ACADEMY
RAMKUNJ, SAHYADRI HOUSING SOCIETY, SHANIWAR PETH, KARAD
9423866425
MH-CET / JEE / JEE - Adv. / AIPMT
Date :
Time : 00:45:00Mins
Marks : 50
TEST ID: 24
PHYSICS
: ANSWER KEY :
1)
5)
9)
13)
17)
21)
25)
c
b
b
b
a
a
b
2)
6)
10)
14)
18)
22)
26)
a
a
d
c
b
c
b
3)
7)
11)
15)
19)
23)
27)
b
a
b
c
b
d
a
4)
8)
12)
16)
20)
24)
28)
c
b
b
b
d
a
a
29)
33)
37)
41)
45)
49)
a
b
d
c
c
a
30)
34)
38)
42)
46)
50)
b
a
c
c
c
a
31)
35)
39)
43)
47)
d
d
a
a
d
32)
36)
40)
44)
48)
a
a
d
d
c
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KOTA ACADEMY
RAMKUNJ, SAHYADRI HOUSING SOCIETY, SHANIWAR PETH, KARAD
9423866425
MH-CET / JEE / JEE - Adv. / AIPMT
Date :
Time : 00:45:00Mins
Marks : 50
TEST ID: 24
PHYSICS
: HINTS AND SOLUTIONS :
1
(c)
ω=F.S=F S cos 90=F S x 0=0
3
(b)
F = mrω2 = mr 2πn 2
Here r = 1.96 + 0.04 =2m
F = 0.5 × 2 × 2× π×5 2= 1× 10π 2
= 100 π2 = 100 × 9.86= 986N
4
(c)
F=mrω2
6
(a)
28
2
Because difference in centrifugal force (F = mr
which is propontional to r)
29
7
(a)
Common ang. speed  after coupling
I1 1 + I2 2
1 (1000)
 =
=
= 50 rad/sec
I1 + I2
2
Loss of K.E. = K.E. initial – K.E. final
= 2.5 kJ
31
11 (b)
x = 5 = 10 sin ωt+α
1
⇒2= sin ωt+α
𝜋
∴ sin ωt+α = sin6
𝜋
⇒ ωt+α =6
13 (b)
F L
Y= ×
ℓ = extension
A ℓ
Y1 = Y2
F1 L1
F2 L2
FL
2F × 2L
=
⇒ 2=
⇒ ℓ = ℓ
A1 ℓ1
A2 ℓ2 πr
4πr 2 × ℓ
16 (b)
Volume of n droplet = volume of single drop

R3 = 64 r3
R = 4mm
18 (b)
𝑘 = 62.8 𝑢𝑛𝑖𝑡
2π
2π
k= ⇒λ=
λ
k
2×3.14
=
=0.1 unit
62.8
23 (d)
34
35
P1 = I1 A1 and P2 = I2 A2
But P1 = σ A1T41 and P2 = σ A1T41
∴ σ T41 A1 = I1A1
σ T42 A2 = I1A2
T2 4 I2
=
T1
I1
T2
I2 1/4
=
= 104 1/4 = 10
T1
I1
T2 = T1 ×10 60000K°
(a)
𝛽 D. λ 1 × 5 × 10−7
=
=
= 1.25 mm
2 2. d 2 × 2 × 10−4
(a)
Q
VC2
100 × 20 × 10−6
V1 =
=
=
C1 C1 + C2
30 × 10−6
= 66.67V
V2 = V – V1 = 100 – 66.67 = 33.33
(d)
R AB = 2 × 10 = 20Ω
3
3
1
i=
=
=
10 + 20 30 10
1
V = i R AB =
× 20 = 2 V
10
V
2
= =
= 0.2 v/m
L 10
(a)
For circular the required centripetal force is
provided by magnetic force.
m v2
mv
I. e. Q v b
∴b=
R
qr
B ≈ 1.6 × 10−8 t
(d)
∅ Nab 100 × 10−4 × 5
Current sensitivity = =
=
i
c
10−8
=5 rad/ µamp
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36 (a)
G=25 Ω , s=2.5 Ω
𝐼𝐺
𝑆
=
𝐼𝑜 𝑆 + 𝐺
2.5
=
2.5 + 25
2.5
=
27.5
25
=
275
1
=
11
37 (d)
ev
M = IA = 2πr 𝐴 = e. f. A. = e. f. π r 2
= VR = 220
V = 220 Volt ∴ I =
44 (d)
2
=
1
VR2 + VL − VC
K. E.1
1
=
k. E.2
2
45 (c)
Longest wavelength for B Series = 36 5R
𝐿𝑜𝑛𝑔𝑒𝑠𝑡 𝑤𝑎𝑣𝑒𝑙𝑒𝑛𝑔𝑡𝑕 𝑓𝑜𝑟 𝐿. 𝑠𝑒𝑟𝑖𝑒𝑠 =
=1.6 × 10−19 × 6.8 × 1015 × 3.14 ×
0.53 × 10−10 2
= 9.596 × 10−24 ≈ 9.6 × 10−24 Am2
39 (a)
a when R is negligible,
1
1
n=
=
2π LC 2π 10−2 × 25 × 10−6
104 103
=
=
10𝜋
𝜋
π
T= 3
milli second
10 sec = π
T 3T 5T
as energy is magnetic at time t = , ,
2 2 2
Therefore, t = 1.57,4.74,7.85 … … milli second
41 (c)
VL = VC
from given relation V =
EV 220
=
= 2.2A
R
100
4
3𝑅
𝜆𝐵 36 3𝑅 27
1
=
×
=
,𝜆 ∝
𝜆𝐿 5𝑅
4
5
𝑣
𝜆𝐵
5
𝜆𝐿 27
=
𝑜𝑟
=
𝜆𝐿 27
𝜆𝐵
5
48 (c)
V
5
One diode is reverse bias I=R = 10 = 0.5 A
2
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