A negative focal length indicates that the lens is a concave lens.

Power (P) = 1/f (in meters). Here, f = 0.2 m, so P = 1/0.2 = +5 D.

Power (P) is given by P = 1/f (in meters). Thus, P = 1/0.25 m = +4 D.

Power is inversely proportional to focal length. If f is doubled, P = 1/f will halve.

Magnification (m) = v/u = 1 when image distance equals object distance.

Using the lens formula 1/f = 1/v - 1/u, we have 1/f = 1/40 - 1/(-30) = 1/40 + 1/30. Solving gives f = 20 cm.

At destructive interference, the intensity is zero because the waves cancel each other out.

When the object distance equals the focal length, the image is formed at infinity.

When the object is at the focal length, the image is formed at infinity.

The focal length f of a mirror is given by f = R/2. Thus, f = 40 cm / 2 = 20 cm.

The focal length f of a mirror is given by f = R/2. For a convex mirror, R = 30 cm, so f = 30/2 = 15 cm.

Using the lens maker's formula, f = R/(n-1) = 20/(1.5-1) = 40 cm.

Using the lens maker's formula, f = R/(n-1) = 30/(1.5-1) = 30/0.5 = 60 cm.

Using the lens maker's formula, f = R/(n-1) = 30/(1.5-1) = 30/0.5 = 60 cm.

Focal length f = R/2 = 30 cm / 2 = 15 cm.

The focal length (f) of a spherical mirror is given by f = R/2. Here, R = 40 cm, so f = 40/2 = 20 cm.

Critical angle θc = sin⁻¹(1/1.33) ≈ 48.6°.

The critical angle θc can be calculated as θc = sin^(-1)(n2/n1) = sin^(-1)(1.00/1.33) ≈ 48.6°.

Speed of light in medium = c/n = (3 x 10^8 m/s) / 1.33 ≈ 2.25 x 10^8 m/s.

The critical angle θc is given by sin(θc) = n2/n1 = 1/1.5, which gives θc ≈ 41.8°.

The speed of light in a medium is given by v = c/n. Here, c = 3 x 10^8 m/s and n = 1.5, so v = 3 x 10^8 / 1.5 = 2 x 10^8 m/s.

Speed of light in medium = c/n = (3 x 10^8 m/s) / 1.5 = 2 x 10^8 m/s.

Wavelength in medium = λ/v = λ0/n = 600 nm / 1.5 = 400 nm.

Using the formula θc = sin^(-1)(1/n), where n = 2.0, we find θc = sin^(-1)(1/2) = 30°.

Using the formula sin(θc) = n2/n1, we have sin(θc) = 1.00/2.00, leading to θc ≈ 30°.

Using the formula sin(θc) = n2/n1, where n1 = 2.0 (medium) and n2 = 1.0 (air), we find sin(θc) = 1.0/2.0 = 0.5, leading to θc = 60°.

Critical angle θc = sin⁻¹(n2/n1) = sin⁻¹(1.00/2.00) ≈ 30°; thus, maximum angle of incidence for total internal reflection is 60°.

The speed of light in a medium is given by v = c/n, where n is the refractive index. If n > 1, the speed decreases.

The speed of light in a medium is less than that in vacuum, given by v = c/n, where n > 1.

The speed of light in a medium is given by v = c/n, where n is the refractive index. If n > 1, then v < c, meaning the speed decreases.