There are two main types of appliances and chargers available in the electronic world: those that use single-voltage and those that can accommodate dual-voltage.
Single-voltage devices have a small voltage range (such as 100–120V). They are able to handle small voltage fluctuations but will not be able to handle India’s 240V power supply — if used, you will likely end up with a smoking piece of electronics!
Some examples of single-voltage appliances are older hair dryers and irons. There should be a tag, compliance plate, or stamp on the appliance letting you know the voltage compatibility (see the example shown above). If they are not rated at 240V, don’t even bring these items with you. They are a fire hazard and, at best, will break on your trip.
Dual-voltage devices have a larger voltage range, for example, 110V/240V. These devices are able to handle up to 240V and are “safer” to bring to India.
Some examples of dual-voltage devices include newer electric shavers, toothbrushes, laptops, Kindles (as shown in the image), tablets, smartphones, cell phones, cameras, and battery chargers. No transformer or converter is required to use these items in India — you just need the India Power Adapter that you have already wisely purchased.