An antenna is a device to transmit and/or receive electromagnetic waves. An antenna must be tuned (matched) to the same frequency band as the radio system to which it is connected, otherwise reception and/or transmission will be impaired. Most cell phone antennas are as long as ¼ the wavelength of the wave they are transmitting or receiving. Your cell phone (usually) operates at a range of frequencies around 1900 MHz. What is the length (in cm) of the antenna in your phone?

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in chemistry, adhesion and cohesion are attractive forces that exist between molecules. they hold the molecules together from each other. they are different in that adhesive force exists between molecules of different substance while cohesive force happens between molecules of same substance.

adhesion between water and glass causes water molecules at the edge of water and glass interface to climb up the wall in a narrow glass tube. this is called capillary action. cohesion is what gives glass its shape and causes water to form a droplet.