The focal length of a concave lens is negative, so it is -15 cm.

Power (P) = 1/focal length (f). Therefore, f = 1/P = 1/(-2) = -0.5 m.

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.

Using the mirror formula 1/f = 1/v + 1/u, where u = -30 cm and v = -10 cm, we find f = 15 cm.

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.

Using the lens formula 1/f = 1/v - 1/u, where v = 30 cm and u = -15 cm, we find f = 20 cm.

Using the lens formula, we find the focal length to be -12 cm.

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.

For the image to be at infinity, the focal length must be equal to the object distance, hence f = 60 cm.

Using the lens formula, 1/f = 1/v - 1/u. Here, v = -20 cm (virtual image), u = -10 cm. Solving gives f = 5 cm.

Using the lens maker's formula for a plano-convex lens, f = R/2 = 30 cm / 2 = 30 cm.

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.

The force experienced by a charge q in an electric field E is given by F = qE.

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.

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.

The force experienced by a current-carrying conductor in a magnetic field is known as the Lorentz force.

The force on a charge moving in a magnetic field is given by F = qvBsinθ, where θ is the angle between v and B.

According to Newton's first law, no net force is required to maintain constant velocity.

The formula for calculating kinetic energy is KE = 1/2 mv², where m is mass and v is velocity.

The frequency of a wave is calculated using the formula f = 1/T, where T is the period of the wave.

The magnetic force on a charged particle is given by F = qvBsinθ, where q is the charge, v is the velocity, B is the magnetic field, and θ is the angle between v and B.

The potential energy of an object at height h is calculated using the formula PE = mgh, where m is mass, g is gravitational acceleration, and h is height.

The total power in a series RLC circuit is given by P = VI cos(φ), where φ is the phase angle.

The total power in an AC circuit is given by P = VI cos(φ), where φ is the phase angle.

The work done by a force is calculated using the formula W = Fd, where F is the force and d is the distance moved in the direction of the force.

Gravitational potential energy is calculated using the formula PE = mgh, where m is mass, g is acceleration due to gravity, and h is height.

The angular position of the first minimum in a double-slit diffraction pattern is given by d sin(θ) = mλ, where m = 1 for the first minimum.

The correct formula for the angular position of the m-th order maximum is d sin θ = mλ.

The equivalent resistance in a balanced Wheatstone bridge can be calculated using the parallel formula.

The equivalent resistance of two resistors in series is simply the sum of their resistances: R1 + R2.