Mean optical power launched into an `8 km` fibre is `120 muW` and mean output power is `4 muW`, then the overall attenuation is (Given log `30=1.477`)

If the input and output power of an optical fibre of length 150 m are 10 mu W and 9 mu W respectively then loss in dB/km is approximately

If the input and output power of an optical fibre of length 150 m are 10 mu W and 9 mu W respectively then loss in dB/km is approximately

In the given electric circuit find (a) current (b) power output (c) relation between r and R so that the electric power output (that means power to R) is maximum. (d) value of maximum power output (e) plot graph between power and resistance of load (f) from graph we see that for a given power output there exixts two values of external resistance, prove that the product of these resistances equal to r^2 . (g) what is the efficiency of the cell when it is used to supply maximum power.

A point sound is located in the perpendicular to the plane of a ring drawn through the centre O of the ring. The distance between the point O and the source is l = 1.00 m , the radius of the ring is R = 0.50 m . If the mean energy flow rate across the area encloseed by the ring is (in muW ). Find (x_(0))/(5) . Given, at point O the energy intensity of sound is equal to I_(0) = 30 muW//m^(2) and assuming the damping of the waves is negligible.

A point sound is located in the perpendicular to the plane of a ring drawn through the centre O of the ring. The distance between the point O and the source is l = 1.00 m , the radius of the ring is R = 0.50 m . If the mean energy flow rate across the area encloseed by the ring is (in muW ). Find (x_(0))/(5) . Given, at point O the energy intensity of sound is equal to I_(0) = 30 muW//m^(2) and assuming the damping of the waves is negligible.

A transformer is an electrical device which is used for changing the a.c. voltage. It is based on the phenomenon of mutual induction. It can be shown that (E_(s))/(E_(P)) = (I_(P))/(I_(s)) = (n_(s))/(n_(P)) = K Where the symbols have their standard meaning. For a step up transformer, K gt 1 and for a step down transformer, K lt 1 . The above relations are on the assumption that efficiency of transformer is 100% . In fact, efficiency eta = ("output power")/("input power") = (E_(s) I_(s))/(E_(P) I_(P)) The number of turns in the primary and secondary coils of a transformer are 2000 and 50 respectively. The primary coil is connected to main supply of 120 V and secondary to a night bulb 0.6 Omega . The efficiency of transformer is 80% . Power in primary coil is:

A transformer is an electrical device which is used for changing the a.c. voltage. It is based on the phenomenon of mutual induction. It can be shown that (E_(s))/(E_(P)) = (I_(P))/(I_(s)) = (n_(s))/(n_(P)) = K Where the symbols have their standard meaning. For a step up transformer, K gt 1 and for a step down transformer, K lt 1 . The above relations are on the assumption that efficiency to transformer is 100% . In fact, efficiency eta = ("output power")/("input power") = (E_(s) I_(s))/(E_(P) I_(P)) The number of turns in the primary and secondary coils of a transformer are 2000 and 50 respectively. The primary coil is connected to main supply of 120 V and secondary to a night bulb 0.6 Omega . The efficiency of transformer is 80% . Power in secondary coil is: