Suppose you have a lowpass circuit and a highpass circuit an
Solution
low pass filter : A low-pass filter is a filter that passes signals with a frequency lower than a certain cutoff frequency and attenuates signals with frequencies higher than the cutoff frequency.
High pass Filter :
A high-pass filter is an electronic filter that passes signals with a frequency higher than a certain cutoff frequency and attenuates signals with frequencies lower than the cutoff frequency.
Band pass filter is allowed to pass the some range of the frequency and to make band pass filter we have to first use the high pass filter and than the low pass filter if we interchange the order then the cascading combination will not work as a band pass filter.
high pass filter pass the band which is higher than its corner frequency and the band low pass allowd to pass which is lower than its cutoff frequency so cutoff frequecy of the each filter will no chage
the responce of the band pass filter will look like as below
https://drive.google.com/file/d/0B8qvCRWlWMqUU0c3aGhMWGdNZUk/view?usp=sharing
