Q. What is the expected osmotic pressure of a 0.5 M NaCl solution at 25 °C?
A.
12.3 atm
B.
24.6 atm
C.
6.1 atm
D.
3.1 atm
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Solution
Osmotic pressure (π) can be calculated using the formula π = iCRT. For NaCl, i = 2, C = 0.5 M, R = 0.0821 L·atm/(K·mol), and T = 298 K, resulting in approximately 24.6 atm.
Correct Answer: B — 24.6 atm
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Q. What is the expression for the magnetic field at the center of a circular loop of radius R carrying a current I?
A.
B = μ₀I/(2R)
B.
B = μ₀I/(4R)
C.
B = μ₀I/(πR)
D.
B = μ₀I/(2πR)
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Solution
The magnetic field at the center of a circular loop of radius R carrying a current I is given by B = μ₀I/(2πR).
Correct Answer: D — B = μ₀I/(2πR)
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Q. What is the expression for the magnetic field at the center of a circular loop of radius R carrying current I?
A.
μ₀I/(2R)
B.
μ₀I/(4R)
C.
μ₀I/(2πR)
D.
μ₀I/(4πR)
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Solution
The magnetic field at the center of a circular loop is given by B = μ₀I/(2R).
Correct Answer: C — μ₀I/(2πR)
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Q. What is the expression for the magnetic field B at a distance r from a long straight conductor carrying current I?
A.
B = (μ₀I)/(2πr)
B.
B = (μ₀I)/(4πr²)
C.
B = (I)/(2πr)
D.
B = (μ₀I²)/(2πr)
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Solution
The magnetic field B at a distance r from a long straight conductor carrying current I is given by B = (μ₀I)/(2πr).
Correct Answer: A — B = (μ₀I)/(2πr)
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Q. What is the expression for the magnetic field B at a distance r from a long straight wire carrying current I according to the Biot-Savart Law?
A.
B = (μ₀I)/(2πr)
B.
B = (μ₀I)/(4πr²)
C.
B = (I)/(2πr)
D.
B = (μ₀I²)/(2πr)
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Solution
The magnetic field B at a distance r from a long straight wire carrying current I is given by B = (μ₀I)/(2πr).
Correct Answer: A — B = (μ₀I)/(2πr)
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Q. What is the family of curves represented by the equation xy = c?
A.
Hyperbolas
B.
Parabolas
C.
Ellipses
D.
Circles
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Solution
The equation xy = c represents a family of hyperbolas with varying constant c.
Correct Answer: A — Hyperbolas
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Q. What is the family of curves represented by the equation x^2/a^2 + y^2/b^2 = 1?
A.
Ellipses
B.
Hyperbolas
C.
Parabolas
D.
Circles
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Solution
The equation x^2/a^2 + y^2/b^2 = 1 represents a family of ellipses with semi-major axis a and semi-minor axis b.
Correct Answer: A — Ellipses
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Q. What is the family of curves represented by the equation y = a sin(bx + c)?
A.
Sine waves
B.
Cosine waves
C.
Linear functions
D.
Quadratic functions
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Solution
The equation y = a sin(bx + c) represents a family of sine waves with amplitude a and phase shift c.
Correct Answer: A — Sine waves
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Q. What is the family of curves represented by the equation y = e^(kx)?
A.
Linear functions
B.
Exponential functions with varying growth rates
C.
Logarithmic functions
D.
Polynomial functions
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Solution
The equation y = e^(kx) represents a family of exponential functions where 'k' determines the growth rate.
Correct Answer: B — Exponential functions with varying growth rates
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Q. What is the family of curves represented by the equation y = k/x?
A.
Linear functions
B.
Hyperbolas
C.
Parabolas
D.
Circles
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Solution
The equation y = k/x represents a family of hyperbolas with varying asymptotes depending on the value of 'k'.
Correct Answer: B — Hyperbolas
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Q. What is the final temperature when 200 g of water at 90°C is mixed with 300 g of water at 30°C?
A.
50°C
B.
60°C
C.
70°C
D.
80°C
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Solution
Using the formula m1*T1 + m2*T2 = (m1 + m2)*Tf, we find Tf = (200*90 + 300*30) / (200 + 300) = 70°C.
Correct Answer: C — 70°C
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Q. What is the first derivative of f(x) = e^(2x)?
A.
2e^(2x)
B.
e^(2x)
C.
e^(x)
D.
2x*e^(2x)
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Solution
Using the chain rule, f'(x) = 2e^(2x).
Correct Answer: A — 2e^(2x)
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Q. What is the first law of thermodynamics?
A.
Energy cannot be created or destroyed
B.
Entropy of an isolated system always increases
C.
Heat cannot spontaneously flow from a colder body to a hotter body
D.
The total energy of a system is constant
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Solution
The first law of thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another.
Correct Answer: A — Energy cannot be created or destroyed
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Q. What is the focal length of a concave lens if it forms a virtual image at a distance of 20 cm from the lens?
A.
-10 cm
B.
-20 cm
C.
10 cm
D.
20 cm
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Solution
For a concave lens, the focal length (f) is negative. The virtual image distance (v) is -20 cm. Using the lens formula 1/f = 1/v + 1/u, we can find f. Since v = -20 cm, we can assume u is at infinity, thus 1/f = 1/(-20) + 0, giving f = -20 cm.
Correct Answer: B — -20 cm
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Q. What is the focal length of a concave lens with a focal point at -15 cm?
A.
15 cm
B.
-15 cm
C.
30 cm
D.
-30 cm
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Solution
The focal length of a concave lens is negative, so it is -15 cm.
Correct Answer: B — -15 cm
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Q. What is the focal length of a concave lens with a power of -2 diopters?
A.
-0.5 m
B.
0.5 m
C.
-2 m
D.
2 m
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Solution
Power (P) = 1/focal length (f). Therefore, f = 1/P = 1/(-2) = -0.5 m.
Correct Answer: A — -0.5 m
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Q. What is the focal length of a concave mirror if an object is placed at a distance of 30 cm from the mirror and the image is formed at a distance of 15 cm from the mirror?
A.
10 cm
B.
15 cm
C.
20 cm
D.
25 cm
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Solution
Using the mirror formula, 1/f = 1/v + 1/u. Here, v = -15 cm (real image) and u = -30 cm (object distance). Thus, 1/f = 1/(-15) + 1/(-30) = -1/10, so f = -10 cm.
Correct Answer: A — 10 cm
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Q. What is the focal length of a concave mirror if an object placed 30 cm in front of it produces an image at 10 cm in front of the mirror?
A.
5 cm
B.
10 cm
C.
15 cm
D.
20 cm
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Solution
Using the mirror formula 1/f = 1/v + 1/u, where u = -30 cm and v = -10 cm, we find f = 15 cm.
Correct Answer: C — 15 cm
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Q. What is the focal length of a concave mirror if an object placed at a distance of 30 cm produces an image at a distance of 15 cm?
A.
10 cm
B.
15 cm
C.
20 cm
D.
25 cm
Show solution
Solution
Using the mirror formula, 1/f = 1/v + 1/u; here, v = -15 cm (real image) and u = -30 cm. Thus, 1/f = 1/(-15) + 1/(-30) = -1/10, so f = 10 cm.
Correct Answer: A — 10 cm
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Q. What is the focal length of a convex lens if it forms a real image at a distance of 30 cm when the object is placed at 15 cm from the lens?
A.
10 cm
B.
15 cm
C.
20 cm
D.
25 cm
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Solution
Using the lens formula 1/f = 1/v - 1/u, where v = 30 cm and u = -15 cm, we find f = 20 cm.
Correct Answer: C — 20 cm
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Q. What is the focal length of a lens if it forms a virtual image at a distance of 12 cm when the object is placed at 8 cm?
A.
-24 cm
B.
-12 cm
C.
12 cm
D.
24 cm
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Solution
Using the lens formula, we find the focal length to be -12 cm.
Correct Answer: B — -12 cm
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Q. What is the focal length of a lens if it forms a virtual image at a distance of 15 cm when the object is placed at 10 cm?
A.
-30 cm
B.
30 cm
C.
15 cm
D.
10 cm
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Solution
Using the lens formula 1/f = 1/v - 1/u, we have 1/f = 1/(-15) - 1/(-10) = -1/15 + 1/10 = -1/30, thus f = -30 cm.
Correct Answer: A — -30 cm
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Q. What is the focal length of a lens if it forms an image at infinity when the object is placed at 30 cm?
A.
30 cm
B.
15 cm
C.
60 cm
D.
20 cm
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Solution
For the image to be at infinity, the focal length must be equal to the object distance, hence f = 60 cm.
Correct Answer: C — 60 cm
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Q. What is the focal length of a lens that forms a virtual image at a distance of 20 cm when the object is placed at 10 cm?
A.
5 cm
B.
10 cm
C.
15 cm
D.
20 cm
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Solution
Using the lens formula, 1/f = 1/v - 1/u. Here, v = -20 cm (virtual image), u = -10 cm. Solving gives f = 5 cm.
Correct Answer: A — 5 cm
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Q. What is the focal length of a plano-convex lens with a radius of curvature of 30 cm?
A.
15 cm
B.
30 cm
C.
45 cm
D.
60 cm
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Solution
Using the lens maker's formula for a plano-convex lens, f = R/2 = 30 cm / 2 = 30 cm.
Correct Answer: B — 30 cm
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Q. What is the force between two point charges of +2μC and -3μC separated by a distance of 0.5m in vacuum?
A.
-1.08 N
B.
-0.72 N
C.
1.08 N
D.
0.72 N
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Solution
Using Coulomb's law, F = k * |q1 * q2| / r^2 = (9 × 10^9) * |2 × 10^-6 * -3 × 10^-6| / (0.5)^2 = -1.08 N.
Correct Answer: A — -1.08 N
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Q. What is the force experienced by a charge q in an electric field E?
A.
F = qE
B.
F = E/q
C.
F = q/E
D.
F = q + E
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Solution
The force experienced by a charge q in an electric field E is given by F = qE.
Correct Answer: A — F = qE
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Q. What is the force experienced by a charge q moving with velocity v in a magnetic field B?
A.
qvB
B.
qvB sin(θ)
C.
qvB cos(θ)
D.
qvB tan(θ)
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Solution
The force experienced by a charge q moving with velocity v in a magnetic field B is given by the Lorentz force law: F = q(v × B), which can be expressed as F = qvB sin(θ), where θ is the angle between the velocity and the magnetic field.
Correct Answer: B — qvB sin(θ)
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Q. What is the force experienced by a charge q moving with velocity v in a magnetic field B at an angle θ?
A.
qvB
B.
qvB sin(θ)
C.
qvB cos(θ)
D.
qvB tan(θ)
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Solution
The magnetic force on a charge moving in a magnetic field is given by F = qvB sin(θ), where θ is the angle between the velocity and the magnetic field.
Correct Answer: B — qvB sin(θ)
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Q. What is the force experienced by a current-carrying conductor placed in a magnetic field?
A.
Electromotive force
B.
Lorentz force
C.
Centripetal force
D.
Gravitational force
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Solution
The force experienced by a current-carrying conductor in a magnetic field is known as the Lorentz force.
Correct Answer: B — Lorentz force
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