It depends on the flashlight.
It would.of course, be more interesting if backward installed batteries caused the flashlight to suck in light and cast a beam of darkness - but the real world does not work in this way
It happens when you turn on the flashlight and a circuit is created through the batteries, through the light filament, back down the outside of the batteries to the end of the batteries, etc. Switching off the flashlight breaks the circuit, curtails the chemical reaction in the batteries, and the light goes out.
The flashlight can not be turned on as it no power now.
If you connect positive to positive and negative to negative you will have a 9V battery with twice the current capacity in milliampere hrs than a single batteries. The load then goes between positive and negative paralleled terminals. If you connect one negative of one battery to one positive of the other battery and put the load between the remaining negative and positive terminals you have created an 18 V battery with the same milliampere hr rating as a single battery. If you connect one negative to positive of other battery and the negative of that battery to the positive of the first battery then both batteries with quickly drain and get hot in the process. Contrary to folklore or urban lefends, they do not explode.
If you put the batteries in a flashlight in the wrong direction, the electrical current won't flow properly, preventing the flashlight from turning on. It's important to insert the batteries according to the correct polarity indicated on the device to ensure it functions correctly.
Dead battery -will no longer charge.
If you cross the neg. with the pos. on a battery you could blow up both batteries and also blow the fuses on both cars.
It might explode. It will certainly send toxic gasses into the environment.
What happens when you inadvertently crossed the positive battery terminal from a negative to a positive and a positive to a negative.?Read more: What_happens_when_you_inadvertanly_crossed_the_positive_battery_terminal_from_a_negative_to_a_positive_and_a_positive_to_a_negative.
Did it run before you swapped batteries or did you guess it was a bad battery. Did you have the old battery tested? If it ran before you swapped batteries then i would say you left something unhooked or the battery terminals are cruddy and need cleaned
Rechargeable batteries that are not charged for a long time will still work sufficiently. Batteries that are overcharged will damage the battery.
energy cannot be created. Instead it changes forms of energy. the energy of a battery is chemical energy. the chemical energy from the battery changes to to electric energy when you turn it on. Then it changes again into heat and light energy. That energy will go on and change into some other kind of energy and so on forever.
it means that you can't charge the battery and you need to replace the dead batteries with new ones