Semester 1 is of 40 marks. The syllabus consists of three units (i) Force, Work, Power and Energy (ii) Light (iii) Sound.

**(i) Turning forces concept**; moment of a force; forces in equilibrium; centre of gravity; (discussions using simple examples and simple direct problems).

Elementary introduction of translational and rotational motions; moment (turning effect) of a force, also called torque and its cgs and SI units; common examples - door, steering wheel, bicycle pedal, etc.; clockwise and anti-clockwise moments; conditions for a body to be in equilibrium (translational and rotational); principle of moment and its verification using a metre rule suspended by two spring balances with slotted weights hanging from it; simple numerical problems; Centre of gravity (qualitative only) with examples of some regular bodies and irregular lamina.

**(ii) Uniform circular motion.**

As example of constant speed, though acceleration (force) is present. Differences between centrifugal and centripetal force.

**(iii) Work, energy, power and their relation with force.**

Definition of work. W FS cosθ; special cases of θ = 0°, 90°. W= mgh. Definition of energy, energy as work done. Various units of work and energy and their relation with SI units. [erg, calorie, kW h and eV].

Definition of Power, P=W/t; SI and cgs units; other units, kilowatt (kW), megawatt (MW) and gigawatt (GW); and horse power (1hp=746W) [Simple numerical problems on work, power and energy].

**(iv) Different types of energy** (e.g., chemical energy, Mechanical energy, heat energy, electrical energy, nuclear energy, sound energy, light energy).

Mechanical energy: potential energy U = mgh (derivation included) gravitational PE, examples; kinetic energy K= ½mv^{2} (derivation included); forms of kinetic energy: translational, rotational and vibrational - only simple examples.

[Numerical problems on K and U only in case of translational motion]; qualitative discussions of electrical, chemical, heat, nuclear, light and sound energy, conversion from one form to another; common examples.

**(v) Machines** as force multipliers; load, effort, mechanical advantage, velocity ratio and efficiency; pulley systems showing the utility of each type of machine.

Functions and uses of simple machines: Terms- effort E, load L, mechanical advantage MA = L/E, velocity ratio VR = VE/VL = dE / dL, input (Wi), output (Wo), efficiency (η), relation between η and MA, VR (derivation included); for all practical machines η <1; MA < VR.

Pulley system: single fixed, single movable, block and tackle (Pulleys using single tackle); MA, VR and η in each case.

**(vi) Principle of Conservation of energy.**

Statement of the principle of conservation of energy; theoretical verification that U + K = constant for a freely falling body. Application of this law to simple pendulum (qualitative only); [simple numerical problems].

**(i) Refraction of light** through a glass block and a triangular prism - qualitative treatment of simple applications such as real and apparent depth of objects in water and apparent bending of sticks in water. Applications of refraction of light.

Partial reflection and refraction due to change in medium. Laws of refraction; the effect on speed (V), wavelength (λ) and frequency (f) due to refraction of light; conditions for a light ray to pass undeviated.

Values of speed of light (c) in vacuum, air, water and glass; refractive index µ = c/V, V = fλ. Values of µ for common substances such as water, glass and diamond; experimental verification; refraction through glass block; lateral displacement; refraction through a glass prism, simple applications: real and apparent depth of objects in water; apparent bending of a stick under water. Simple numerical problems and approximate ray diagrams required.

**(ii) Total internal reflection:** Critical angle; examples in triangular glass prisms; comparison with reflection from a plane mirror (qualitative only). Applications of total internal reflection.

Transmission of light from a denser medium (say glass) to a rarer medium (air) at different angles of incidence; critical angle (c) n = 1/sin c.

Essential conditions for total internal reflection. Total internal reflection in a triangular glass prism; ray diagram, different cases - angles of prism (60º, 60º, 60º), 60º, 30º, 90º), (45º, 45º, 90º); use of right angle prism to obtain δ = 90º and 180º (ray diagram); comparison of total internal reflection from a prism and reflection from a plane mirror.

**(iii) Lenses** (converging and diverging) including characteristics of the images formed (using ray diagrams only); magnifying glass; location of images using ray diagrams and thereby determining magnification.

Types of lenses (converging and diverging), convex and concave, action of a lens as a set of prisms; technical terms; centre of curvature, radii of curvature, principal axis, foci, focal plane and focal length; detailed study of refraction of light in spherical lenses through ray diagrams; formation of images - principal rays or construction rays; location of images from ray diagram for various positions of a small linear object on the principal axis; characteristics of images. Sign convention and direct numerical problems using the lens formula are included (derivation of formula not required).

Scale drawing or graphical representation of ray diagrams not required.

Power of a lens (concave and convex) - only definition and basic understanding based on the curvature or thickness of lens. Applications of lenses

**(iv) Using a triangular prism** to produce a visible spectrum from white light; Electromagnetic spectrum.

Deviation produced by a triangular prism; dependence on colour (wavelength) of light; dispersion and spectrum; electromagnetic spectrum: broad classification (names only arranged in order of increasing wavelength); properties common to all electromagnetic radiations; properties and uses of infrared and ultraviolet radiation.

**(i) Reflection of Sound Waves**; echoes: their use; simple numerical problems on echoes.

Production of echoes, condition for formation of echoes; simple numerical problems; use of echoes by bats, dolphins, fishermen, medical field. SONAR.