Physics

The sensitivity of a thermometer is

The sensitivity of a thermometer is
A. All of the above
B. how quickly a temperature change can be detected
C. the difference between the maximum and the minimum temperature
D. the smallest temperature change that can be detected or measured.

Correct Option: Answer is D
The sensitivity of a thermometer is defined as the smallest temperature change that can be detected or measured, NOT how quickly that temperature change can be detected.

The sensitivity of a thermometer is Read More »

An open-tube mercury manometer is used to measure the pressure in a gas tank. When the atmospheric pressure is 101,325 Pa , what is the absolute pressure in Pa in the tank if the height of the mercury in the open tube is 25 cm higher

An open-tube mercury manometer is used to measure the pressure in a gas tank. When the atmospheric pressure is 101,325 Pa , what is the absolute pressure in Pa in the tank if the height of the mercury in the open tube is 25 cm higher
A. 108,986 Pa
B. 165,238 Pa
C. 122,364 Pa
D. 134,645 Pa

Correct Option: Answer is D

density (ρ) = 13600 kgm−3; g =9.8ms−29.8−2

Patm =101,325 Pa; ρ=13600 kgm-3

Pabs=Patm+ρgh

⇒Pabs=101,325+13600 x 9.8 x 0.25

⇒Pabs=101,325+33320

⇒ Pabs=134,645Pa

An open-tube mercury manometer is used to measure the pressure in a gas tank. When the atmospheric pressure is 101,325 Pa , what is the absolute pressure in Pa in the tank if the height of the mercury in the open tube is 25 cm higher Read More »

A beam of light travelling in water is incident on a glass which is immersed in the water. The incident beam makes an angle of 40o with the normal. Calculate the angle of refraction in the glass. [Refractive index of water = 1.33, Refractive index of glass = 1.5]

A beam of light travelling in water is incident on a glass which is immersed in the water. The incident beam makes an angle of 40o40 with the normal. Calculate the angle of refraction in the glass.

[Refractive index of water = 1.33, Refractive index of glass = 1.5]
A. 29.36o
B. 25.37o
C. 37.21o
D. 34.75o

Correct Option: Answer is D
n1=1.33; n2=1.5; i=40°; r= ?

from snells law:

n1 x sini=n2x sinr

⇒1.33 x sin40°=1.5 x sinr

⇒sinr=0.5700

⇒r = sin−1 (0.5700)

⇒ r= 34.75

A beam of light travelling in water is incident on a glass which is immersed in the water. The incident beam makes an angle of 40o with the normal. Calculate the angle of refraction in the glass. [Refractive index of water = 1.33, Refractive index of glass = 1.5] Read More »

How much work is done against the gravitational force on a 3.0 kg object when it is carried from the ground floor to the roof of a building, a vertical climb of 240 m?

How much work is done against the gravitational force on a 3.0 kg object when it is carried from the ground floor to the roof of a building, a vertical climb of 240 m?
A. 7.2 kJ
B. 4.6 kJ
C. 6.8 kJ
D. 8.4 Kj

Correct Option: Answer is A
The work done against the gravitational force is calculated using the formula W = mgh, where m is the mass of the object, g is the acceleration due to gravity (approximately 9.8ms2 on Earth), and h is the height. Substituting the given values, we get W = 3.0 kg * 9.8m/s29.8/2 * 240 m = 7.2 kJ. Therefore, the correct answer is ‘7.2 kJ’.

How much work is done against the gravitational force on a 3.0 kg object when it is carried from the ground floor to the roof of a building, a vertical climb of 240 m? Read More »

A relative density bottle has a mass of 19 g when empty. When it is completely filled with water, its mass is 66 g. What will be its mass if completely filled with alcohol of relative density 0.8?

A relative density bottle has a mass of 19 g when empty. When it is completely filled with water, its mass is 66 g. What will be its mass if completely filled with alcohol of relative density 0.8?
A. 47 g
B. 52.8 g
C. 37.6 g
D. 56.6

Correct Option: Answer is D
Let mb=mass of empty bottle,

mw=mass of water only and

ma= mass of alcohol only

given; mb=19g

mb+ mw = 66g

mb+ ma = ?

R.d=0.8

R.d=mass of alcohol
⇒massofalcohol/massofequalvolumeofwater
⇒ mass of equal volume of water = mw=66-19=47g

⇒0.8 = ma/47

⇒ma=0.8×47 =37.6g

; mb + ma = 19+37.6=56.6g

A relative density bottle has a mass of 19 g when empty. When it is completely filled with water, its mass is 66 g. What will be its mass if completely filled with alcohol of relative density 0.8? Read More »

An object is placed 35 cm away from a convex mirror with a focal length of magnitude 15 cm. What is the location of the image?

An object is placed 35 cm away from a convex mirror with a focal length of magnitude 15 cm. What is the location of the image?
A. 26.25 cm behind the mirror
B. 10.5 cm behind the mirror
C. 26.25 cm in front of the mirror
D. 10.5 cm in front of the mirror

Correct Option: Answer is B

f= -15cm (diverging mirror); u=35cm; v=?
=(1 )/(f )= (1 )/(u )+(1 )/v
=(1 )/(-15 )= (1 )/(35 )+(1 )/v
=(1 )/(15 )- (1 )/(35 )=(1 )/v
=(-2 )/21= (1 )/(v )
=(-21 )/(2 )= -10.5cm

An object is placed 35 cm away from a convex mirror with a focal length of magnitude 15 cm. What is the location of the image? Read More »

A piano wire 50 cm long has a total mass of 10 g and its stretched with a tension of 800 N. Find the frequency of the wire when it sounds its third overtone note.

A piano wire 50 cm long has a total mass of 10 g and its stretched with a tension of 800 N. Find the frequency of the wire when it sounds its third overtone note.
A. 800 Hz
B. 600 Hz
C. 400 Hz
D. 200 Hz

Correct Option: Answer is D
The frequency (f) of a stretched string can be calculated using the formula:
F =1/(2L ) √(T/u)
where:
L is the length of the string,
T is the tension in the string,
μ is the linear mass density of the string.
The linear mass density (μ) is given by the formula:
μ = m/(L )
where:
m is the mass of the string,
L is the length of the string.
Given:
L=50 cm=0.5 m
T=800 N
m=10 g=0.01 kg
First, calculate the linear mass density:
u= 0.01/(0.5m ) = 0.02kg/m
Now, substitute the values into the frequency formula:
F =1/(2 x 0.5 ) √40000
f=200 Hz

A piano wire 50 cm long has a total mass of 10 g and its stretched with a tension of 800 N. Find the frequency of the wire when it sounds its third overtone note. Read More »

A 35 kΩ is connected in series with a resistance of 40 kΩ. What resistance R must be connected in parallel with the combination so that the equivalent resistance is equal to 25 kΩ?

A 35 kΩ is connected in series with a resistance of 40 kΩ. What resistance R must be connected in parallel with the combination so that the equivalent resistance is equal to 25 kΩ?
A. 40 kΩ
B. 37.5 kΩ
C. 45.5 kΩ
D. 30 kΩ
Correct Option: Answer is B
To find the equivalent resistance of the combination, let’s denote the given resistances as follows:
R1=35kΩ (the first resistor)
R2=40kΩ (the second resistor)
The total resistance (Rtotal) of two resistors in series is the sum of their individual resistances:
Rtotal=R1+R2
Rtotal=35kΩ+40kΩ
Rtotal=75kΩ
Now, let R be the resistance connected in parallel with the combination. The formula for the total resistance of two resistors in parallel is given by:
Rtotal1=R31+R1
Given that Rtotal should be equal to 25 kΩ, we can write the equation as:
1/25 kΩ=1/75 kΩ+1/R
Now, solve for R:
1/R=1/25 kΩ−1/75 kΩ
1/R=3/75 kΩ−1/75 kΩ
1/R=2/75 kΩ
R=75 kΩ/2
R=37.5kΩ
Therefore, the resistance R that must be connected in parallel is:
B. 37.5 kΩ

A 35 kΩ is connected in series with a resistance of 40 kΩ. What resistance R must be connected in parallel with the combination so that the equivalent resistance is equal to 25 kΩ? Read More »

A block of mass 0.5 kg is suspended at the 40 cm mark of a light metre rule AB that is pivoted at point E, the 90 cm mark, and is kept at equilibrium by a string attached at point D, the 60 cm mark, as shown in the figure above. Find the tension T in the string. [Take g = 10ms−2 ]

A block of mass 0.5 kg is suspended at the 40 cm mark of a light metre rule AB that is pivoted at point E, the 90 cm mark, and is kept at equilibrium by a string attached at point D, the 60 cm mark, as shown in the figure above. Find the tension T in the string.

[Take g = 10ms−2 ]
Correct Option: Answer is
W = mg = 0.5 x 10 = 5 N

Since it’s light, neglect the weight of the metre rule.

The effective tension T acting in the vertical direction = T sin 30°

From the second condition of equilibrium, sum of clockwise moments equal sum of anticlockwise moments

Taking moment at E
⇒ T sin 30° x 30 = 5 x 50

⇒ ∴T=250
T = 250/15 = 16.67N

A block of mass 0.5 kg is suspended at the 40 cm mark of a light metre rule AB that is pivoted at point E, the 90 cm mark, and is kept at equilibrium by a string attached at point D, the 60 cm mark, as shown in the figure above. Find the tension T in the string. [Take g = 10ms−2 ] Read More »

A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns?

A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns?
A. 20
B. 250
C. 200
D. 500

Correct Option: Answer is D
Ep = 2.2kV = 2200V; Es=110V; Ns=25; Np=?

=Ep/Es = Np/Ns

= 2200/110 = Np/25

=110 × Np = 2200 × 25

=Np = 55,000/110

∴Np = 500 turns

A step-down transformer is used on a 2.2 kV line to deliver 110 V. How many turns are on the primary windings if the secondary has 25 turns? Read More »

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