Complete the following table based on Ohm's law Voltage (volt V) Current (ampere A) Resistance (ohm Ω ) 12 ...... 4 ....... 2 3 6 3 ......

Given, voltage V = 12 V Resistance R = 4 Ω Current can be calculated using the formula I = V R I = 12 4 = 3 A Now, in second case current I = 2 A resistance R = 3 Ω Voltage can be calculated using the formula V = I R V = 2 × 3 = 6 V o l t In third case Voltage V = 6 V current I = 3 A Resistance can be calculated using R = V I 6 3 = 2 Ω Voltage (volt V) Current (ampere A) Resistance (ohm Ω ) 12 3 4 6 2 3 6 3 2

An object of size 70 mm is place at 27 cm in front of a concave mirror of focal length 18 cm . At what distance from the mirror should a screen be placed so that a sharp focussed image can be obtained? Find the size and nature of the image.

Height of the object h 1 = 70 mm = 7 cm Object distance u = - 27 cm The focal length of a concave lens f = - 18 cm Let the image distance be found be v . According to the mirror formula, 1 f = 1 v + 1 u ∴ 1 v = 1 f - 1 u ∴ 1 v = 1 - 18 - 1 - 27 ∴ 1 v = 9 - 18 × 27 v = - 54 cm The screen should be placed 54 cm to the left of the pole to get a sharp image. Let the height of the image be found be h 2 . Magnification M is given by, M = - v u = h 2 h 1 ∴ - - 54 - 27 = h 2 7 ∴ h 2 = - 14 cm The height of the image is - 14 cm . As the image height and image distance are negative, The image is real, inverted, and enlarged.

Light enters from air to glass having refractive index 1.50 . What is the speed of light in the glass? The speed of light in a vacuum is 3 × 10 8 m s .

Given: Refractive index, n = 1.5 Refractive index, n = speed of light in vacuum speed of light in a medium ⇒ 1 .50 = 3 × 10 8 speed of light in the glass ⇒ Speed of light in glass = 2 × 10 8 m s