What properties of microwaves make them suitable for
a. Heating food rapidly
b. Carrying digital signals to and from a satellite ?

Calculate the value of g in the following two cases: (a) If a mango of mass 1/2 kg falls from a tree from a height of 15 metres, what is the acceleration due to gravity when it beigns to fall? (b) Consider a satellite orbiting the Earth in a circular orbit of radius 1600 km above the surface of the Earth. What is the acceleration experienced by the satellite due to Earth's gravitational force?

A long copper wire of diameter 2 mm carries a current of 1.5 A. a. What is the magnetic field (B) at a perpendicular distance 1 m from the middle of the wire? b. What is the field (B) on the surface of the conductor? c. At a distance 1 mm from the axis, what is the value of the magnetic field?

Arrange the following statements in correct sequence: 1. These vapours condense to form tiny droplets of water. 2. The water droplets come together to form large water droplets. 3. The heat of the sun causes evaporation of water from the surface of the earth, oceans, lakes, rivers and other water bodies. 4. The large water droplets become heavy and the air cannot hold them, therefore, they fall as rains. 5. Water vapour is also continuously added to the atmosphere through transpiration from the surface of the leaves of trees. 6. Warm air carrying clouds rises up. 7. Higher up in the atmosphere, the air is cool. 8. These droplets floating in the air along with the dust particles form clouds.

(i) A mobile phone has a passcode of 6 digits. What is the maximum number of attempts one makes to retrieve the passed. (ii) Given four flags of different colours, how many different signals can be generated if each signal requires the use three flags, One below the other?

Two submarines are approaching each other in a calm sea. The first submarine travels at a speed of 36 km h^-1 and the other at 54 km h^-1 relative to the water. The first submarine sends a sound signal (sound waves in water are also called sonar) at a frequency of 2000 Hz. (a) At what frequency is this signal received by the second submarine ? (b) The signal is reflected from the second submarine. At what frequency is this signal received by the first submarine. Take the speed of the sound wave in water to be 1500 m s^-1 .

A person suffering from a disease caused by Plasmodium, experiences recurring chill and fever at the time when (a) the sporozoites released from RBCs are being rapidly killed and broken down inside spleen (b) the trophozoites reach maximum growth and give out certain toxins (c) the parasite after its rapid multiplication inside RBCs ruptures them, releasing the stage to enter fresh RBCs (d) the microgametocytes and megagametocyte are being destroyed by the WBCs

i. Light has several properties like reflection, refraction etc. When light travels from an optically denser medium to a rarer medium ? a. What happens to the light at the interface ? b. give a demonstration for total internal reflection. c. What are the technological applications of total internal reflection in nature? Briefly explain it.

A lady cannot see objects closer than 40cm from the left eye and closer than 100cm from the right eye. While on a mountaining trip, she is lose from her team. She tries to make an astronomical trip, from her reading glasses to look from her teammates. (a) Which glass should she use as the eyepiece? (b) What magnification can she get with relaxed eye?

Suppose the rod with the balls A and B of theprevious problem is clamped at the centre in such a way that it ca rotate freely about a horizontal axis through the clamp. The system is kept at rest in the horizontal position. A particle P of the same mass m is dropped from a heigh h hon the ball B. The particle collides with B and sticks to it. a. Find the angular momentum and the angular speed of the system just after the collision. b. What should be the minimum value of h so that the system makes a full rotation after the collision.

Sita is a owner of confectionary. She got an order from one of her customers to prepare 150 loaves of bread for a birthday party. On her making process of bread, though there is a time constrain, she prepared the dough and kept it aside undisturbed for few hours. Later she made the required number of breads and delivered to customer on time. A day after the party, customer appreciated Sita for the soft and good quality of bread that she supplied to party. (a) Why Sita kept aside the dough undisturbed? (b) Name the living organism involved in the process. (c) What are the products of the process? (d) How this process enhances the quality of food?