A voltameter has internal resistance r ohms and range V volts.The value of resistance used in series to convert it into a voltmeter of range 4V volts is

In Potentiometer experiment,the balancing length with a cell in the secondary circuit is found to be 480cm.when a resistor of 8 ohm is connected in parallel to the cell the balancing length is found to be 420cm.The internal resistance of the cell is

Three unequal resistors in parallel are equivalent to a resistance 1 ohm. If two of them are in the ratio 1:2and if no resistance value is fractional the largest of the three resistances in ohms is

One junction of thermo couple is at 0⁰C and the other junction is heated .Maximum current in the thermo couple is observed when hot junction is at 240⁰C.The temperature of the hot junction at which the direction of current reverses is

A cell of emf 2V and negligible resistance is connected in series with a resistance of 5 ohm,and a potentiometer wire of resistance 10 ohm.what is the potential drop per cm if the length of the potentiometer wire is 10m.The emf of a cell which is balanced by 750cm long wire is

A galvanometer of resistance 100Ω gives full scale deflection with 5mA current.To convert it into a 5 volt range voltmeter,the value of resistance connected in series is

Four bulbs each marked 40 W. 250 V are connected in series with 250 V source. The total power output is

An electrical meter of internal resistance 20Ω gives full scale deflection when one milliampere current flows through it.The maximum current that can be measured by using three resistors of resistance 12Ω each,in milliamperes is

Two wires of same material and same length have their resistances in the ratio 5:7.The ratio of the masses of the wires is

In a thermo couple the cold junction is at 30⁰C.The temperature of inversion is found to be 540⁰C,Then the neutral temperature is