The speed of airflow on the upper and lower surfaces of a wing of an aeroplane is \(v_1\) and \(v_2\) respectively. If \(A\) is the cross-section area of the wing and \(\rho\) is the density of air, then the upward lift is:
1. \(\frac12\rho A(v_2-v_2)\)
2. \(\frac12\rho A(v_1+v_2)\)
3. \(\frac12\rho A(v_1~^2-v_2~^2)\)
4. \(\frac12\rho Av_1~^2+v_2~^2\)

 

Subtopic:  Bernoulli's Theorem |
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A body is thrown with a velocity of \(9.8\) m/s making an angle of \(30^\circ\) with the horizontal. It will hit the ground after a time:
1. \(1.5\) s
2. \(1\) s
3. \(3\) s
4. \(2\) s

Subtopic:  Projectile Motion |
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A radioactive element \({ }_{90} \mathrm{X}^{238}\) decays into \({ }_{83} Y^{222}\). The number of \(\beta\)-particles emitted are:
1. 1
2. 2
3. 4
4. 6

Subtopic:  Types of Decay |
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The minimum excitation potential of Bohr's first orbit in a hydrogen atom is:
1. \(3.6\) V
2. \(10.2\) V
3. \(13.6\) V
4. \(3.4\) V
Subtopic:  Bohr's Model of Atom |
From NCERT
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A gas expands \(0.25~\mathrm{m^3}\) at constant pressure \(10^3~\mathrm{N/m^2}\), the work done is:
1. \(250~\mathrm{N}\) 
2. \(250~\mathrm{W}\) 
3. \(250~\mathrm{J}\) 
4. \(2.5~\mathrm{erg}\) 

Subtopic:  Work Done by a Gas |
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The work done in increasing the size of a soap film for \(10~ \mathrm{cm} \times 6~ \mathrm{m}\) to \(10~ \mathrm{cm} \times 11~ \mathrm{m}\) is \(3\times 10^{-4}\) J. The surface tension of the film is:
1. \(1.0 \times10^{-2}\) N/m
2. \(6.0 \times 10^{-2}\) N/m
3. \(3.0 \times 10^{-2}\) N/m
4. \(1.5 \times 10^{-2}\) N/m

 

Subtopic:  Surface Tension |
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A parallel plate condenser is filled with two dielectrics as shown in the figure. The area of each plate is \(A~\text m^2\) and the separation is \(d\) meter. The dielectric constants are \(K_1\) and \(K_2\) respectively. Its capacitance in farad will be: 
             

1. \(\frac{2\varepsilon_{_0}A}{d}\Big(\frac{K_1+K_2}{K_1K_2}\Big)\)
2. \(\frac{2\varepsilon_{_0}A}{d}\Big(\frac{K_1K_2}{K_1+K_2}\Big)\)
3. \(\frac{\varepsilon_{_0}A}{d}\Big(\frac{K_1+K_2}{2K_1K_2}\Big)\)
4. \(\frac{\varepsilon_{_0}AK_1K_2}{2(d_2K_1+d_1K_2)}\)

 

Subtopic:  Dielectrics in Capacitors |
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A luminous object is placed at a distance of 30 cm from the convex lens of focal length 20 cm. On the other side of the lens, at what distance from the lens can a convex mirror of radius of curvature 10 cm be placed in order to have an upright image of the object coincident with it?
1. 30 cm
2. 60 cm
3. 50 cm
4. 12 cm

Subtopic:  Lenses |
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A battery of emf \(10~\text V\) and internal resistance of \(0.5~\Omega\) is connected across a variable resistance \(R.\) The maximum value of \(R\) is given by:
1. \(0.5~\Omega\)
2. \(1.000~\Omega\)
3. \(2.0 ~\Omega\)
4. \(0.25 ~\Omega\)
Subtopic:  EMF & Terminal Voltage |
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For a gas \(\frac{R}{C_v}=0.67.\) This gas is made up of molecules which are:
1. monoatomic
2. polyatomic
3. mixture of diatomic and polyatomic molecules
4. diatomic
Subtopic:  Specific Heat |
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