Back motor effect of loaded generators? The back motor effect (see Counter-electromotive force) is the counter torque which opposes the rotational motion of the coils in a generator when the generator is under load.
The back motor effect depends upon the load connected to the generator. The more load, the more current will be produced which will increase the counter torque. But to produce more current, the normal torque will also increase. So, shouldn't this balance the effect? If it does, then why do small generators change sound (nearly shutting down) when load in increased on them?
 A: 
But to produce more current, the normal torque will also increase.

Maybe yes, maybe no.
The counter-torque acts to slow the generator shaft.  If the load increases and the input torque (from e.g. a turbine driving the shaft) stays the same, that net torque will slow the generator down.
Usually, a governor of some kind acts to increase the torque so the speed, frequency and output voltage remain constant. Thats governor has to act to increase the input torque and power to match the load.
If there is no active element increasing the input torque, the shaft will slow, the voltage will drop, which will decrease the current and power out, until the generator eventually comes into equilibrium at a slower speed and lower voltage and frequency. 
But normally we choose to control those to keep them constant.  
A: For increase in current you don't need to increase the torque. You have an armature with a potential on its terminals. To increase the current you need to reduce the impedance connected to the terminals of the generator. Just connect appliances in parallel. There will be more current in the armature of the generator because when you connect load ( appliances in parallel )with the generator the impedance reduces this increases the current. The increase in current with increase the back motor effect that will reduce the speed of the shaft.
A: A small shutting down on increasing resistance because the small generator has no ability to produce such current to perform such load.  If the load is equal to the ability of the generator then it will not shut off.
