Question: I read this book called Practical Electronics for Invetors,and it says that one of the ways to increase magnetic field strenght of solenoid is to increase the current or increase the number of turns.

That got me thinking,why do induction heaters and induction coupled plasma use small number of turns and high current? Why not increase the number of turns and then decrease the current so there is less problem with coil overheating?

I played with online solenoid magnetic field strenght calculator,and as I kept increasing number of turns it kept giving stronger magnetic field without increasing current.So logicaly that extra energy must come by voltage right? I mean energy doesnt just magicaly appear out of nowhere,and since the current stays the same,it must mean that solenoid with more turns needs higher voltage,is that correct?

Can I avoid heat problems by using solenoid that have large number of turns so I can power it with high voltage low current instead of low voltage high current that conventional solenoid with small number of turns would require?

edit : I want to say big thanks for all of you who came here to help me,I didnt expect so much help so fast,this ElectronicsEngineering section seems friendliest of all stackexchange sections I tried,I love you all <3

Answer: 
Especially considering size and weight, I'd use a PIC 10F200 microcontroller. It has a oscillator built in, and needs no other components other than a bypass cap to drive a LED. It can also run from a reasonably wide voltage range, including 3.7 V.

The internal oscillator is good to a few percent. The instruction cycle rate is 1 MHz driven by that oscillator. At 1-5 kHz, you have a minimum of 200 cycles per blink period, or 100 cycles per blink phase. That's plenty to do a little counting to decide when to toggle the LED state.

The output pins can source or sink a few mA, and you can gang three of them together to get more current capability to drive the LED directly with a resistor in series to set the current.
Once you started actually talking about your problem, it became clear that you were indeed asking an xy question. The question you really want answered, is "How can I identify a drone by blinking its orientation lights?" or even better, "I'd like to identify a drone by blinking its orientation lights. What should I be thinking about?". Although the latter is a bit vague, I agree.

With that in mind, it's clear that blinking the orientation lights at 1 to 5 kHz will not do you any good. If you're looking at it with your eyes, kHz is way beyond visual fusion rate, so there's no way your eye can distinguish between drones with different flash rates. If you're looking at it with a camera, 1 to 5 kHz is far beyond the frame rate you'll get with any reasonable camera. To identify a 5 kHz flash rate from camera footage requires a minimum of 10,000 frames per second, and that is hardly standard kit.

All things considered, it would seem your best bet is to point a telescope at it with a very high-sensitivity detector and a frequency detection circuit. Such a detector would require a very narrow bandpass filter at the LED wavelength. 

So, rather than insisting that what you want to know is how to flash an LED, you need to start thinking about just exactly what you want to do from a system viewpoint, and determine if you CAN identify a drone by flashing its LEDs. Only after you've done your system calculations should you start worrying about how to do it.