Ø
The magnetising force at
the centre of a circular coil varies directly as the current, varies directly
as its radius and varies inversely as its radius.
Ø
The ratio of Ah
efficiency to Wh efficiency of a lead-acid cell is always greater than one.
Ø
The resistance offered
to the radial leakage (at right angles to the flow of useful current) of
current is called insulation resistance of the cable.
Ø
The SI unit of electric
intensity is V/m (volt/metre) or N/C (newton/coulomb).
Ø
The SI unit of magnetic
flux is weber.
Ø
The unit of absolute
permittivity of a medium is farad/metre.
Ø
The unit of capacitance
is coulomb/volt i.e. farad
Ø
The various electrical
instruments can be divided into absolute instruments and secondary instruments.
Ø
The working principle of
thermo-couple ammeter is based on the Seebeck effect.
Ø
Trickle charging of
battery is used to balance the open-circuit losses.
Ø
Two heaters, rated at
1000 W, 250 volts each, are connected in series across a 250 Volts 50 Hz A.C.
mains. The total power drawn from the supply would be 500 watt.
Ø
Two similar electric
charges of 1 C each are placed 1 m apart in air. Force of repulsion between
them would be nearly 9 × 109
newton.
Ø
Two types of e.m.f are
dynamically induced and statically induced.
Ø
Trickle charging of a
storage battery helps to keep it fresh and fully charged.
Ø
Sulphation in a
lead-acid battery occurs due to incomplete charging.
Ø
The constant-voltage
system of charging a lead-acid cell has the advantage of reduced time of
charging and increased cell capacity.
Ø
The capacity of a
lead-acid cell does not depend on its rate of charge.
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