The rechargeable batteries for a laptop computer need a much smaller voltage than what a wall socket provides. therefore, a transformer is plugged into the wall socket and produces the necessary voltage for charging the batteries. the batteries are rated at 9.0 v, and a current of 268 ma is used to charge them. the wall socket provides a voltage of 120 v. (a) determine the turns ratio of the transformer. (b) what is the current coming from the wall socket? (c) find the average power delivered by the wall socket and the average power sent to the batteries.

What produces light and all other electromagnetic waves? a) the photoelectric phenomena b) heated metals c) charged particles d) radioactive samples (pls explain if you can : )

What happens to light waves from a star as the star moves away from earth?

We want to calculate the total metabolic heat generated by a singing canary taking into account heat transfer by radiation, convection and exhaling air. the air temperature is 20 oc, canary’s body internal and surface temperature is 33oc, external body surface convective heat transfer coefficient is 25.2 w/m2 .k, temperature difference between the inhaled and exhaled air is 4.3 oc, the ventilation rate is 0.74 cc of air per second, specific heat of air is 1.0066 kj/kg.k and density of air is 1.16 kg/m3 . assume the canary’s body to be a cylinder with 7 cm diameter and 9 cm length, and heat exchange is from the side as well as the top and bottom of cylinder. calculate 1) the net rate of heat lost by radiation, assuming heat gained by the bird through radiation from the surroundings is 11.5 w; 2) rate of heat transferred by convection to the surrounding air; 3) rate of heat transferred in the exhaling air without considering any internal evaporation; 4) total metabolic power.